There are quite a few out there of these SSO passing system. Here is a list of the ones I have found to be interesting enough to consider.
RPXNow - http://www.rpxnow.com
Gigya - http://www.gigya.com
ClickPass - http://www.clickpass.com
HybridAuth - http://hybridauth.sourceforge.net
With HybridAuth - you get all the code and the connection request will say <YOURSITE> is requesting access from the different IdP (Identity Providers) but it tends to have more bugs then the others. Gigya is FREE and everyone loves FREE. Rpx grabs lots of data but you will end up paying $10/month. Clickpass just uses the OpenID system and you can get an OpenID mod from ESASE here.
I am hoping that Boonex will be smart enough to incorporate some option into their 7.1 or 8.0 release that allows using multiple Identity Providers so people are not asked to input all their data to join, since it seems thats where everyone is headed. There could be an Admin feature that allows site owners to activate this feature if they want to open up the community.
Let me know if you are willing to share your code and I can give you my email.
Thanks in advance.