The LUGNET Guide is a searchable database of nearly all known LEGO sets. It uses a hierarchical organization by theme but also can be searched by set name, and browsed by year of issue. Each entry includes, where available, the year released, a piece count, number of minifigs, and MSRP. The entries also contain links to the Peeron database, for the parts inventory, and to PICSL.
LUGNET members have the ability to rate the set (using a 0-100 scale in increments of 10 scale) as well as leave comments, and note that they have (publically and/or privately), copies to sell or want to buy copies.