Social Network -
I had lot of doubts on how ringo and alike (sites) implemented login functionalities to access the contact address book / list. That was the reason of these findings.
They are many sites, which offers social networking service - these sites can also help you to send mails to all your friends avaliable in your address book at Hotmail, GMail, Yahoo ,AOL, GMX or Web.de email Accounts
I have seen ringo in action, but not others. Many sites like ringo do exist... heres a few list for you...I am not sure to say all the below mentioned sites have the same functionalities like ringo.
Bebo, Hi-5, Linked-In, Tribe, Spoke, Friendster, Ryze, ZeroDegrees, Ecademy, RealContacts, Ringo, MySpace, Yafro, Everyone’s Connected, Friendzy, FriendSurfer, Tickle, Evite, Plaxo, SMS.AC, 43Things, Yafro, Squiby and WhizSpark
Check http://www.google.com/Top/Society/Relationships/Friendship/Services/?il=1 &
http://www.google.com/Top/Computers/Internet/Cyberspace/Online_Communities/?il=1 for more sites...
I was thinking, how to do the same if i had too.... This thinking led me to google....and i conclude my views as below...
1) You may need to legally have a tie up with Hotmail, GMail, Yahoo ,AOL, GMX or Web.de to offer those services....
2) Otherwise you can use GMail API and Yahoo Java API (I am not sure if these method of access is illegal and can be done, i have not experimented either)
3) You may also check on Jabber.org (XMPP), they write 'transport' / 'service agent' components which can talk to Yahoo, AOL. AIM, MSN, ICQ, IRC & etc.,
All these are my findings and not experiments. You may need to contact the respective site owners to know more about doing this... Please read their Conditions, Privacy Policy, TOS (Terms of Service), AUP (Acceptance use policy), Disclaimer and then act.
I found something related to Information Security, Copyright Act, etc.,, (Hope this would throw some more knowledge on you)
http://www.consumer.ftc.gov/articles/0272-how-keep-your-personal-information-secure
http://www.nq.com/2012_NQ_Mobile_Security_Report.pdf
http://en.wikipedia.org/wiki/DMCA
http://www.bbb.org/
http://www.consumer.gov/idtheft/index.html
http://www.getnetwise.org/
More on Social Networking...
http://www.infoanarchy.org/wiki/index.php/Social_Networking
http://en.wikipedia.org/wiki/Social_network
Let me leave you alone to think.... :)