Things that could have been canon, but weren't.
Season 6 Thanksgiving with Buffy and Dawn's aunts. Missing scenes between Wrecked and Gone, so canon with all that that entails - smutty and sad.
Digbert has been nominated for Best Original Character in round 31 of the Sunnydale Memorial Fanfiction Awards.
Sometime post-Gone, a Spike and Buffy tryst. A character study.