[Gundam-Dude]

Typically Vocaloid is associated with trance but there are a few other genres that can be incorporated such as jazz, rock, classical, etc. It's not strictly trance in particular since vocarock and vocajazz take up just as many singles. The two Vocaloid songs I stepped for this are produced by OSTER Project so obviously it's more upbeat jazz-esque. I wouldn't associate it as anime either because Vocaloid is a music making software and there are no actual animations that exist for it (though Black Rock Shooter is getting it's own anime adaptation in 2010).

Vocaloid music is endless and it'd be impossible to download every single song unless you've been around from the very beginning of the program's release with MEIKO and KAITO and searched all over nicovideo and vocaloid community. Hell, my Vocaloid music folder is only like 4GB and that's only a small percentage compared to the millions of other singles that are uploaded each and every day.