Gnash has been talked about to death. If anyone tech savvy could contribute to Gnash that'd be great - but they're horribly legally cautious - their team is all people who NEVER used Adobe's Flash Player, at least so they claim.

- Edit -

And of course while Gnash's latest version - I hear - are actually rather nice at supporting flash 9, flash 10 support isn't exactly complete. But I'm looking forward to seeing what happens here. I just don't want to get my hopes up.