http://archive.shriftweb.org/ this is an enormous archive that's really user friendly and one i used to browse a lot
http://scribes.darkstarfic.com/ also a great archive devoted to angel/angelus stories
http://www.tdsos.com/darkerside/ this is less angel focused but still an interesting collection of fic from the buffyverse. she links to some of the huge bnf's from that time: annie sewell-jennings, kita, yahtzee....
http://www.thechicagoloop.net/yahtzee/chivalry/ one of my favorites just because it's so gorgeously designed
http://www.thechicagoloop.net/yahtzee/insect/ and yahtzee is a great writer in general so her entire loop is worth checking out
if i come up with anything else i'll be sure to let you know! and maybe some of my friends will add stuff to this entry....you never know!
happy reading (and writing!)