http://en.wikipedia.org/wiki/Approval_voting
Basically, you check yes or no for everyone, and the winner is the one with the most "yes" votes. Less expressive than IRV, but also simpler to understand and tabulate.
Belatedly: thanks for sharing. It does seem an easier sell, because the counting process is so easy to understand. It's not as favorable to third parties as IRV, because "[X] Minor [X] Major" obviously doesn't carry as much weight as "[1] Minor [2] Major", but at least it still kills the spoiler effect. While IRV seems more "pure" in an information theory sense, Approval is elegant in its simplicity.
That's mostly my views as well, yeah. There are a couple (narrow) weird cases with IRV, too... but IRV is unquestionably a tremendous improvement over FPTP.
"the real effect would be seen if we elected Congress that way as well."
Elaborate on that a bit - I know it's popular to say that Congress has a low approval rating, but no one votes for "congress" - they vote for their congresspeople, who typically have high approval ratings. There may well be other effects I'm not spotting, though...
Honestly, I'm in favor of any modifications to winner-take-all. "None of the Above" would be a major win for the protest vote, with a huge meta-electoral effect even if it never wins. And while it would boost morale and turnout for presidential years, the real effect would be seen if we elected Congress that way as well.