Cowboy Bebop is what kicked it off for me. Outlaw Star was a lot of fun, but coulda used more cowboy style shit on the soundtrack. Watching Space Dandy now and while it's not quite a space western, it's pretty fun to me.
Anything else I should check out?
That latter one sounds fun as fuck!
Disclaimer: Episode 1 is the worst of the whole series, but from E2 it's consistently good.