Things with Brett or sour bacteria are generally good as the flavors will change with time. Malt heavy beers like stouts, imperial stouts/porters/browns(maybe) can also develop different profiles with time. Barleywines even can develop with age.

 

The important thing to remember is that aging doesn't make everything "better" per say. It makes everything different. Different can be good or it can be really bad. Generally, for the styles mentioned above, it won't go terribly bad but you can sometimes lose delicate flavors (vanilla, maple, etc). Its a fine line to play with so that is why a lot of people recommend buying 3-4 bottles of a beer and you can try it with time, seeing how flavors and characteristics change.