I recall one that has Obi-wan somehow finding himself back in time & deciding to correct his mistake of letting Anakin, survive, promptly goes into the Jedi Temple to kill him. Apparently, Anakin was raised differently (I think related to Qui-Gon surviving?) & was very willing to be killed as part of the master/padawan bond thingy. Er, it probably focused on Obi-wan more.
Another one had him react to him back premonition in prequel three or some such by escaping to Naboo with Padme & living there until the force urged him back into the fold.
Edit: At least one is by <a href='http://www.obaona.com/fanfiction.htm' target='_blank' rel='nofollow'>obaona</a>.
<a href='http://www.obaona.com/fanfiction/thewatersedge.htm' target='_blank' rel='nofollow'>The Water's Edge</a> for the former. The Obi-Wan of Ep. III is dumped in an alternate universe by the Force - one where Anakin hasn't turned, the Sith are gone, and Qui-Gon is alive and well. Among other things . . . No spoilers, written well before RotS ever came out.