Gmail seems to be the email provider du jour and, with an exclusive invitation requirement to join, you may find yourself asking friends and strangers for an invite. If you already have Gmail, you'll probably keep receiving new invitations to “hand out” to anyone who will take them.
I recently stumbled across a dumping ground for all of my invites that seems to work pretty well. Isnoop.net Gmail Invite Spooler is willing to take them off your hands as soon as you get them and will match up the invites to people eager to get one.
For those of you who already have Gmail, this service is quick and easy, and it will save you from clogging up the main feeds with invitations notices every time you get a new batch.
If you're looking to get a Gmail account, then you can just as easily sign-up to receive an invite as soon as one becomes available.