There's a variety of albums you can get, depending onwhat you're after. There's a Bob Dylan tribute called Is It Rolling Bob?; a triple CD(!) box set of Beatles covers; and there are millions of versions of soul and gospel songs given the Jamaican treatment all over the shop; the easiest one to find is the Trojan R'N'B box set.
One of the troubles with reggae is that sometimes they aren't copyrighted, so there are tons of covers around, but they can't be put on albums because the publishing is never sorted out, or permission gained. A major bummer.