I'm turning into a great fan of HybridAuth
It is rather new, untested product (and as the older people here know I'm not using such cutting edge, unpopular, half broken things by principle, still I made an exception for that one, which is a recommendation on its own I guess
). It has some problems and typical diseases of a young product, but... It works. And it was designed EXACTLY to cater to my needs as a browser games designer. It is not some crappy OpenID script or social network integration script. No, it is a "connect me with" script. You just edit the config file and enter ALL providers you want and that's it. A total abstraction layer, after config file you don't even know, and don't need to know, if you are connected to Facebook or Twitter or Google or Yahoo!. It just do its things. The newest version has also some functions to post on user walls (Facebook and Twitter I think), but I have not tested it yet. Anyway, it seems to be an overall solution that cater to ALL possible social networks/OpenID related needs of a BBG designer.