Microsoft's Live ID absolutely supports this when signing up for, among other things, Hotmail accounts, Messenger accounts, etc. It follows the same basic process as Yahoo, including the $0.50 charge that's partially donated to charity.
Microsoft's implementation has the fun feature that all mail to the "kid" needs to be approved by he parent. Very fun if a college student puts in the wrong age which triggers those notices to go to the admin account for he college. You need to call customer support to fix this. This was not a fun call.