I guess you could call me a Japanophile. I love learning about Japanese cuisine, and I eagerly collect Japanese kitchen items. I became enamored with bento boxes a while ago, and now I have three different styles of bento boxes that serve various purposes. What they all have in common is that they are convenient, easy to clean, and fun.
The Old-Fashioned Wooden Bento Box With Furoshiki Cloth Wrapping (shown in above photo)
This style of bento box is a bit unwieldy due to its size and the fact that you have to keep it upright. When I'm packing a lunch to take to the office, this isn't the box I choose, as I don't enjoy carrying this on the subway. I do, however, love the aesthetics of it, and I take it to picnics (I packed two of these for my hanami picnic a few weeks ago!) or I serve food in these at home when I have guests over. People love unwrapping the furoshiki cloth and finding a wooden box inside full of delicious food.
The dividers are removeable for easy cleaning, and the wood is lacquered, which keeps it from absorbing food odors and makes it waterproof. I purchased these boxes on eBay from the seller JAPAN-BARGAIN, they have an inventory of these and call them "Japanese Hakoya Ume Wooden Bento Lunch Box."
The Modern Stackable Cylindrical Bento
This is the workhorse that I take to the office for lunch. There are four stackable containers that fit in this temperature-controlled metal cylinder that can stay hot or cold, and it comes with a nylon bag that has a shoulder strap. I simply sling it over my shoulder along with my purse, and I'm ready to hit the pavement and head for the office on the subway. This is actually too large for a whole lunch, but it's perfect for two meals; lunch and an afternoon snack. My lunch usually goes in two containers, and I put something healthy like nuts, berries, vegetable sticks, or fresh fruit for snacking later in the day.
Called a "Mr. Bento," it's made by Zojirushi and is found online at many sources.
The Small Plastic Bento
This small bento is made of plastic with tight-fitting lids. It's two-tiered and held together with a nylon band. There are chopsticks enclosed, and one compartment has a removeable divider. This is really wonderful for smaller meals and snacks, and is super-portable. It fits in my purse or backpack!
J-Box has a wide selection of this kind of bento box - check them out.
(Images: Kathryn Hill and Amazon)
TW Salt Mill by Wil...

This is the authentic Bento website:
http://en.bentoandco.com/
it has an amazing selection.
Bentos are great for portion control and making sure you have variety in your diet
I just went online and bought the Mr. Bento. I can't wait to try it out!
I am so in love with my Mr. Bento. The only bad thing about working from home is that I don't get it use it anymore. Though sometimes I'm tempted to pack lunch in it anyway, just for fun.
I've been using bento boxes for my lunches for many years now and love it! They pack a surprising amount of food for their size and really I just feel so cool using one! I've bought all of mine at www.j-list.com. But you can buy them from Amazon and ebay too! All mine have Totoro and other cute stuff wholely unsuitable for a grown woman but I do what I want! Just remember to NEVER microwave the lids, even if it says you can (they always shrink).
The Mr. Bento also comes in a smaller size, with only 3 containers -- the Ms. Bento. That's what I have.
The small plastic type come in a variety of sizes, from small boxes meant for kids to 'men's size' 800 ml, and lots of designs (plain, simple, cute, traditional patterns or panda shaped). There's also 2 to 3 layer 'jyubako' boxes meant for multiple people. Big range in quality too, from cheap plastic models to high-end, very expensive, handmade wooden models. Good mid-range is Hakoya brand, made from better plastics and more traditional colors/designs.
I'm, uh...somewhat of a nerd and collector of the things.
...that's 800 plus mL, up there. I forget the plus sign doesn't show up in comments for some reason.
The average woman usually needs a 600ml box, a man would need about 800ml. Give or take on both accounts, of course.
Be sure to keep this in mind when shopping! The right size may look way too small, but when packed properly it holds A LOT of food.
Properly = tightly packed with no gaps; half grain, quarter protein, quarter veggies, and fruit and dairy as gap fillers.