Each mixtape's preceded by a brief chat about the genre / style he's covering, The Ghettotech mixtape is particularly good.
Currently also enjoying free downloads from H.W. - A Year's Worth of Worry (right click) Lyrical, poetic, introspective hip-hop from Boston. Seems to be popular across the blogosphere / music sharing culture. Looking into his label Delusional at the moment, so expect a full review shortly.
I'm also digging the lazy slurtronica of Kember Norton, slow, meandering, unfinished pieces of ambience that gradually build emotional potency; something like Oren Ambarachi or Mum if they'd been raised on cider in the west country. Lovely dreamscape stuff. Direct download.
And there's more from DFRNT over at his website. Can this guy do no wrong? There's an awesome remix of Origin Unknown just gone up recently.