One of my favorite game-series since... 1996, maybe? Hmm, don't remember, it was too long ago. XD There are three main official games (four if you count the unfinished JJ3 alpha), plus four Christmas specials.
...Have info! Just be aware that I love the series and am quite biased when talking about it, though. ;)
Jazz2 Online, the current best source for Jazz1 & Jazz2 levels, tilesets, music, and the community's hub. Jazz2City, the previous best source of levels, tilesets, music and community, now resurrected as an archive. :) [Although, it seems to go up and down.]