Been listening to a lot of grime/dub-step recently. Basically it's like the UK's form of hip-hop mixed with garage and drum & bass.
Kode 9 & The Spaceape are fantastic. I found out about them from the Children of Men soundtrack, and Michael Caine loves them, so... suck it, America.
Roots Manuva has been around for awhile and is prolly one of the bigger names in the UK hip-hop world. Plus he hangs out with the Arctic Monkeys.
Finally, you can't mention garage without mentioning my fave, Dizzee Rascal. While I can't claim to understand most of the things he says... the man is phenomenal. Dance wiv me.