In a very nice post, Brooklynguy (whose blog I’ve begun reading in earnest and I’ve linked to) brought up a point that I think many people miss about the purpose of cellaring wine. A wine cellar isn't just a trophy cabinet or a hoard of treasure. I've said before that it is an extension of your kitchen, a type of root cellar. There are many excellent wines that aren't true vin de garde, but are excellent accompaniments to food and really shine with a with a couple of years of cellaring. Once you start to think of wine in this way, I think it helps to develop a much more sophisticated appreciation for wine in general. If your wines for daily consumption are all of the buy-today-to-drink-tonight variety you'll be missing a whole spectrum of enjoyment.
Here is a short list of wines that are very reasonable that I have found to gain character with a little age (2-3 years post release).
Baudry Cuvée Domaine Chinon
Dom. Ste. Anne St. Gervais
Clos Roche Blanche côt
Gamot and Cayrou Cahors
Felsina CC Riserva
All Muscadet from Marc Olivier, Luneau-Papin, Bregeon, Landron (see David Lillie's excellent article in The Art of Eating).
What are some little wines that you cellar?