Did you try looking looking for it on the webpages of the emus?
Seriously though, if the authors wanted to make their work a collaborative project I'm sure they would've done so already. Yabuse is an open source project, so programmers that know any useful code they submit to it will probably be used. Also, there's the issue of SSF's author only speaking japanese, which makes doing a project with english speaking people kinda tough.
Ok, now look Oalboukharey, I think you've really missed the point here. You've been posting various ideas you've had on cool stuff to do for the Dreamcast for a while now. Some of your ideas have had merit, and others not so much. But regardless, you haven't seemed to realize the reason none of the things you're suggesting have or ever will be do. Well I'll spell it out for you. The real reason is, so far no one has had the skills, patience, desire, and most importantly time to do them. You don't have to like it, but the truth of the matter is all the great ideas in the world are useless if left unimplemented.
So, what are you going to do about it? You can either give up right now, and quit posting ideas that by now you must realize would've already been thought of and done before if it were feasible. Or, you can go out there and learn a little bit about the things you're suggesting people do, and figure out if they're practical, and how to implement them yourself. For instance, you want a better Saturn emulator for the Dreamcast? Well as I said Yabuse is an open source project, meaning anyone can read it's code and sumbit new code to be used in it. Even you. If you want it to get better, go out there and make it happen. Otherwise, quit wasting people's time.