I don't think there's any centralized place. But Larry has the hook-up on every single remix ever created, so I suggest stealing his Winamp playlist.
Also, I protest this poll for not having an "All of the Above" selection.
A place such as that would take a hell of a lot of effort. Sure, you can gather up all the tracks from OCR, VGMix and all the C64/Amiga sites, but then you'd have to find out what each one was covering (which here at least isn't complete). Then think of all the Japanese sites like SSH, Levo Lution, Quasar, et al, and translating them. For the competitions such as IMC you may have to provide your own hosting too.Nearest thing to a central for VG remixes at the moment is ThaSauce. Otherwise just let Larry do all the work, or at least when he actually releases another