This is cool stuff: Three Hundred Mechanics, a site that aspires to come up with 300 new game ideas. (Although not "new" as in "there never was anything remotely like it... that would be extremely hard, if possible at all.) This is an ongoing process, by the way... there's currently 58 ideas listed.
I would point out some highlights, but there's just too much here. I'll definitely keep an eye on this site. ^_^