1) Unroll.me (www.unroll.me)
2) FanMix (www.fanmix.com)
3) SaneBox (www.sanebox.com)
4) The Email Game (www.emailga.me)
You can also reply to the mails and like any game, you get points for doing that. The timer also makes it entertaining and not a boring task to do like it would have been if you had been manually selecting and dealing with mails. As for now, The Email Game only works for Gmail and Google Maps.