So simple, and yet we rarely take the time to do it. We make sure the wine bottle is on the table, for goodness sake, but a pretty carafe of ice water? Hardly ever.
We love restaurants that leave a bottle of cold water on the table after the waiter fills our glasses. We can refill at will, no need to wait for a server to come do it for you. Why not afford guests the same ease?
No one has to ask (which, really, people never do) or get up from the table and awkwardly fumble through your kitchen ("Oh, do you have a Brita? Or should I just get tap?"). And in the flurry of cooking dinner for guests, we sometimes forget about water altogether, much less refills.
Get a pretty pitcher, fill it with water, and shove it into the fridge while you're cooking; it'll be cold by the time dinner is served. Then you can add some lemon if you want (or cucumber, as pictured above, if it's appropriate with the food).
It's an extremely simple gesture, but sometimes ample cold water feels like a luxury.
Related: Flat, Bubble, or Flavored: Do You Serve Water with Dinner?
(Image: Roland Glukhov via Shutterstock)
TW Salt Mill by Wil...

Great idea that is often overlooked!
Great idea! I have and love the Vignelli carafe from the Metropolitan Museum of Art, but it only holds about 4 glasses' worth of water. Any suggestions for larger pitchers that are also lightweight?
We have one which looks like this but was cheap (i.e. not from Crate & Barrel) and is easy to hold, although you have to remove the lid to pour. And it's glass, which is nice, but it's not so fancy as to intimidate people. Plus, it holds about a half gallon of whatever you want to put in it.
My mom uses an old 1.5 liter Lorina lemonade bottle (with the wire bail lid) which she fills with tap water and keeps cold in the fridge. It serves four people easily and is easy to pour. Plus, it looks fantastic!
This is probably the single most important thing to me at a dinner party. I love drinking water with dinner, I don't love constantly having to interrupt everything to get more, the pitcher is totally key to me. I am personally quite partial to this vase/pitcher from Ikea but it probably doesn't fit with some fancier settings.
I use old clear wine bottles with the labels removed. One at each end of the table, they take up very little room.
We use two large oldschool italian wine carafes that we put in the fridge in advance - plus use our glass penguin jars for carbonated water as well. People really appreciate it!
I use carafes. They are about liter size and I place them on costers down the table so that guests can reach usually. I try to fill them and put them in the fridge beforehand so they can indeed be taken from fridge to table. I sometimes intersperse with mineral water bottles.