First, from TecheBlog, the Top 10 Strangest Lego Creations -- and not just sculptures, but working...things, like a fully functional air conditioner, knitting machine, or harpsichord.
Eric Harshbarger is a very prolific Lego sculptor. From mosiacs to sculptures to puzzle sets, monuments, architecture, portraits, and pop culture icons, he's done it all.
Minifig's Lego photoset has lots of great stuff, from scenes to bands to famous people. Below are two from his famous people series: Socrates and Neil Gaiman.
Via Bibi's Box.
There are many creative things you can do with Legos, like kill yourself. Flickr photoset The Lego Suicides demonstrates.
Via Bibi's Box.
The Little Artists create miniature replicas of modern artworks in Lego. The Walker Art Gallery has an exposition of their work, Art Craziest Nation. It's probably even better if you know about modern art.
A new favorite blog of mine: Vignette Bricks. Each post features a new mini scene in Lego, by a variety of artists. Lots of movie scenes and the like, particularly Star Wars.
The Brothers Brick is another nice Lego minifig blog, with lots of models of science-fiction tv icons.
Also via pootling.
The Art of the Brick is the gallery of talented brick artist Nathan Sawaya. He does large-scale mosaics, scenes, and replicas of objects in addition to tabletop scultpures and other works. One of his most impressive works is his Han Solo encased in carbonite (Lego artists have a thing about Star Wars). But since you've probably already seen that in the TecheBlog article, I'll show you this big pencil instead. And Oscar.