It's the genre that I found in the late 90's when hip-hop started to change.  Trip-hop is 

  Lots of good stuff here so far, I'll throw up some randoms I've found over the years.  Seems to be a line between trip-hop and downtempo, but I'll roll w/ what could be both.  
Old, but hey, that whole album was amazing
Screenatorium is definitely worth checking out as a whole.  I've been impressed w/ their catalog.