Velvet Sugar is a mash-up, by Go Home Productions (aka Mark Vidler), who puts them together as seamlessly as anyone. His imaginative "Ray of Gob.", which mixed Madonna and the Sex Pistols seems to pop up somewhere every few months, as does this bizarre juxtaposition: the Velvet Underground/Archies "Velvet Sugar."
Am album of recent work, including the Stones-Temptations "Rolling Confusion", T-Rex/Stones "2000 Lightyears from Bolan" can be downloaded (via Rapidshare) on his site (and there's video too).
Another curious mash-up of the Stooges and Salt n' Pepa by 2 Many DJs is posted at the end of this post on Pogo a Go Go.