how about cloth napkins? it's the little things that make life better.
http://www.anthropologie.com/anthro/catalog/productdetail.jsp?subCategoryId=&id=883086&catId=HOME-TABLETOP-NAPKINS&pushId=HOME-TABLETOP-NAPKINS&popId=HOME-TABLETOP&sortProperties=&navCount=45&navAction=middle&fromCategoryPage=true&selectedProductSize=&selectedProductSize1=&color=mut&colorName=MUSTARD&isSubcategory=&isProduct=true&isBigImage=&templateType=

If they like wine, maybe a beautiful decanter or glasses along with a bottle?

I currently have an obsession with appetizer plates and cocktail napkins, they come in such cute fun styles, so maybe a small set?

How about a collection of bar tools and a cocktail recipe book?

Or some pantry friendly appetizer goodies (crackers, olives, smoked salmon, and the like) along with a nice platter?

I have a lot of ideas, but not knowing more about what the couple already has, it's hard to say.

Board games good for groups (Apples to Apples is a favorite with my group of friends and Settlers of Catan is awfully fun, too, but only for 4 to 8 players, I think), pretty serveware like salad bowls, platters, that sort of thing. Decent glassware, perhaps? A bunch of clear glasses in different patterns would make it easier to know whose glass is whose during a party and the two things I NEVER have enough of when I'm hosting are glasses and serving dishes.

Maybe throw in a printed and laminated copy of Mark Bittman's 101 appetizers list? I'm pretty sure I'd find that helpful and fun.

Some possible ideas:

A whimsical bottle opener: http://www.anthropologie.com/anthro/catalog/productdetail.jsp?subCategoryId=&id=973507&catId=HOME-KITCHEN-GADGETS&pushId=HOME-KITCHEN-GADGETS&popId=HOME-KITCHEN&sortProperties=&navCount=70&navAction=middle&fromCategoryPage=true&selectedProductSize=&selectedProductSize1=&color=070&colorName=GOLD&isProduct=true&isBigImage=&templateType=

Pretty dish towels they may not splurge on:
http://www.anthropologie.com/anthro/catalog/productdetail.jsp?subCategoryId=&id=770110&catId=HOME-KITCHEN-DISHTOWELS&pushId=HOME-KITCHEN-DISHTOWELS&popId=HOME-KITCHEN&sortProperties=&navCount=115&navAction=middle&fromCategoryPage=true&selectedProductSize=&selectedProductSize1=&color=crl&colorName=CORAL&isSubcategory=&isProduct=true&isBigImage=&templateType=

This set of entertaining and cookbooks:
http://www.williams-sonoma.com/products/bride-and-groom-boxed-cookbook-set/?pkey=ccookbooks%7Cctlcbkref

Also I'm sure they'd appreciate any help stocking their liquor cabinet. A nice bottle of scotch or vodka with rocks glasses or wine would probably be welcomed.

Sounds like a fun task!

I would look at Dean & Deluca and the food offerings at William-Sonoma. Depending on your budget you can get them a monthly subscription to wine or cheese, frozen apps or breakfast pasteries (the croissants at WS are very good), tons of delicious nibbles on offer. It sounds like they're busy and when I'm busy but craving a party I always wish I had something easy to serve up.

Or, because my taste spans a wide spectrum, what about a Whirly Pop and a selection of gourmet popcorn with a list of fun topping ideas (this site has listed some if you do a search - like lime and salt w/ chili powder, or kettle corn, even PB)? Always a fun late night snack or good with movie night.

a set of 20 or so little cocktail plates for appies, very handy!

i like cake stands because they have such a small footprint, and i can crowd other platters under the pedestal.

if they travel, how about a serving piece from that area, or a tablecloth?

I think a well put together set is always a good gift -- a dessert set (plates w/platter, cake stand, & server) or a tea/coffee set.

Or one great piece like a Chemex coffeemaker from the Handblown Series
or a Sorapot.

Or extremely generous multiples of a frequently used and abused item (beverage glasses, appetizer plates, napkins) so that they don't worry about losing or ruining a few.

I love the Apples to Apples suggestion, as well as the cake stand. I would do a Penzey's sampler, like a hot cocoa set or the basic starter set, and make a recipe book of some fun and easy appetizers. Or a really good coffee with a French press and maybe a coffee service. Or a cheese plate and knives. Or a wine rack with a couple of starter bottles. Or maybe a bunch of candy dishes/dip bowls.

This has me rethinking my registry! =)

A case of inexpensive quaffing wine is a great thing for entertaining.

Ok, I hate to be a killjoy because everyone has come up with good suggestions, especially the board games idea, but as a newlywed who just purged several non-registry wedding gifts during the recent kitchen cure, I am to encourage you to stick to the registry unless you know for sure that your brother and his fiancée really want non-registry items. Maybe there are some items that fit the entertaining theme.

am to = have to

A book of cocktails and appetiser recipes.

One of my favorite entertaining/ kitchen items is a multicolored set of graduated mixing/serving bowls from Crate and Barrel. I got mine several years ago, but I have seen variations of it around in multiple places. The biggest bowl is great for salad, the smallest bowl is good for nuts or olives. When we have a casual part or bbq those bowls get filled with different sorts of snacks and always look festive.

Another favorite is Asian tableware, sushi plates, small square plates, rice bowls, tea cups, saki cups, dipping sauce bowls... You can find lots of styles and good prices at some Asian groceries. I also like World Market for these types of things.

A big wooden salad bowl and nice serving spoons is a classic.

If you are feeling extravagant, how about a grill?

Hi Everyone! Christine here and I'm loving these suggestions. My boyfriend and I are going out gift-hunting tonight after work so these have definitely put some good thoughts in my head. I live in a small-ish town so half the problem is working with selections in local shops!

In response to JMooney's comment, I do know they specifically want non-registry (more personal) gifts. Their registry isn't very extensive (I took a look at it to make sure mine weren't on it/didn't clash with it) so they definitely will get everything on that list from the wedding gifts alone!

be sure to include a gift receipt with whatever you get! things i wish i had:
- nice ice tongs
- colored cocktail napkins (to hide wine stains)
- appetizer plates
- large serving platters
- sauce boat (weird but true)
- reusable chopsticks (wood!)

Another really useful, but not particularly exciting entertaining item is good coolers. We have 2 big ones and they get used all summer long for parties, both by us and by our friends asking to borrow them...

Fondue pot! Seriously why doesn't anyone gift those anymore? I bought a nice electric one a couple years ago and have used it for cheese, chocolate, and stock for a hot pot style dinner.

What about a large ceramic serving bowl from a local artist? They are visually appealing filled and empty and/or they could always hang it on the wall if they are short on space.

Cloth cocktail napkins and small plates to replace paper ones are great. Extra cookie sheets to heat up hor d'ourves always come in handy. If you are looking to splurge, the countertop beertender is a big hit at parties.

Wine glass charms.

Vase.

Pitcher or Platter - their dishes may have a companion piece, and then that wouldn't be straying too far from the registry.

Everyone has such good suggestions. I'll just come out against the author's advice to buy a picnic basket. No one ever uses the big fancy ones. We ebay'ed ours.

Maybe not a picnic basket but a waterproof picnic BLANKET is always a great option. We ADORE ours and use it regularly along with the collapsable cooler case. Both live in our trunk and have been lifesavers everywhere from the beach to the park to the grocery store! Maybe not an "entertaining" gift, but certainly useful and wanted!

Cheese board
appetizer plates from CB2 - they have really nice and trendy ones
wine decanter or a nice wine bottle opener
platters
games like guesstures
wine glasses or martini glasses

Wine glass charms is a great idea (you can never have too many of those, can you?) and maybe a decanter and a Vinturi (http://www.vinturi.com/). We love our Vinturi and use it all the time. Plus, it would be good for parties where the wine is poured quickly and you don't have the time (or the will) to let each bottle sit out long enough.

As a newlywed I would have loved off-the-registry entertaining-oriented gifts. I felt obligated to register for essentials (many of which I received, thanks to my lovely and generous family and friends), but would have been thrilled to receive beautiful appetizer or dessert plates, a cheese board, cloth napkins, etc.

A nice ice bucket.

On the picnic theme, we love and actually use our picnic backpack... it has plates, silverware and glasses (plastic) in one compartment, room for food in the other compartment and 2 detachable wine sleeves on either side. Plus corkscrew - don't forget the corkscrew.

Speaking of that, a good corkscrew, like a Screwpull...

If you have a Japanese store near you, a sake set is very reasonably priced. Looks great on a shelf and you could throw in a bottle of sake for them too.