As for contacts and the address book: + http://code.google.com/apis/contacts/

+ http://developer.yahoo.com/addressbook/

+ http://msdn.microsoft.com/en-us/library/bb463989.aspx

Stop using the password anti-pattern (http://adactio.com/journal/1357)

Facebook has a nice auth flow that http://www.billmonk.com uses. I'd suggest that.

Oh, and hire a visual designer. A strong visual design goes a lot farther than any copy or lock icons ever will.