I like you, muxtape. I still think the concept of making a mix with no particular recipient in mind clashes with my old-fashioned idea of what mix tapes and CDs are supposed to accomplish i.e. make someone want to kiss your mouth.
Still, I appreciate its brevity (12 songs per mix, maximum) and it's nice to jump in and hear an occasionally well-curated 45 minutes of music from a complete stranger. That said: tremble.muxtape.com.