Beer aging thoughts:
1. Buy your beers in brown bottles only.
2. Keep them away from heat and light.
3. Don't try it with "session" beers, meaning your "garden variety" (not meant to insult) lagers/pilsners and ales (brown, pale, wheat, fruit, etc).
4. Higher alcohol is better for aging-helps preserve the beer. Examples of this include IPA's, most "imperial" offerings of standard styles and barleywines.
5. Bottle-conditioned is better/best as the yeast added to the final product and bottled with it will continue to help mature and protect the beer. It may result in a slightly higher ABV in a year or two as the beer conditions.
I have slightly more patience than CB&B and bluebeer, err, bluebear (), but not much. I have some 2-3 year old Brooklyn beers (Black Chocolate Stout and Monster) and 3-5 year old Samichlaus and Bigfoot, but most times I am too lazy to mark the year on the beer and throw it in a box and wait to drink it.
Hope that helps some.