I agree that Daniel Bryan could use an alterate finisher. The Yes/No Lock is believable for Bryan as he's someone with a more normal size and it points out Bryan's technical expertise. However, a problem with a submission finisher is that it's not going to beat guys who are the upper level babyfaces like Cena, Orton and Sheamus. The closest Bryan has come is when he applied the Yes Lock to Sheamus in their two out of three falls match a few months ago. Sheamus didn't submit, but he passed out from the pain, thus giving Bryan a fall during the match. The Yes/No Lock would work on just about everyone else, I think.
For an alternate finisher, I think that Bryan would need something that's similarly believable. A power move such as a powerbomb or chokeslam won't cut it because Bryan doesn't have the size and strength to really make the moves pop as a finisher. Off the top of my head, I think that Bryan would be better served with a move that's simple to perform but carries a good deal of impact with it. You know, a move that gets a pop or groan from the crowd when they see what he's going for or when he hits or misses the move. Something like a Sweet Chin Music type of superkick would work for Bryan, but I think it'd work best if it was one of those moves that just came out of nowhere like HBK's superkick would sometimes or like when Sheamus goes for his Brogue Kick. Having an elaborate set up for the move, like when HBK "tunes up the band" or Sheamus thumps his chest while yelling Brogue would make the move a little cheap. For a move like that, an good alternative might be Daniel Bryan's diving/flying headbutt. It's an easy move to pull off, it delivers a lot of impact and the fans pop for it. They popped for it last night when he went for it and landed it on Cena. If Bryan was to make the move a legit alternative finisher, it'd work out nicely. After all, I can't remember the last time I saw someone use the move. Bryan's the only guy in WWE that uses it, that much I do know.