Roswell fic: Back in the day.
I was never a big fan of past-life Roswell stories -- not sure why, just never cared for them. Then these three fics came along, and they were just far too groovy to be ignored. Each takes a look at one of Roswell's alien's past and explores it in detail, creating vivid, involving histories for each character. All are beautifully written. Check 'em out.
Half-Life by Elizabeth.
By Twilight by Kate.
Translucence by Danilise.
Pyrophobia by Ins is a fascinating post-Shanshu Wesley fic.
techsupport@demon.com by Perri Smith is a fic I loved from the moment I set eyes on it -- it's a story (well) told entirely through e-mails, at turns funny and suspenseful.
Angel fic: