Microsoft is really getting busy on iOS today -- first we saw Kinectimals released for the platform, then it was the new SkyDrive app, but last week we missed seeing a brand new Halo app built for the iPhone (and presumably Windows phone devices as well). This one is a little more useful than the Bungie Mobile app from a while back; Halo Waypoint will not only show you your stats out of game, but help you out while you play. You can see games in progress, and even use the included maps (which were originally in the official strategy guide) to see almost real-time positions for you and your friends while you play. That's pretty cool -- it's a second screen for Halo.
You can also create custom challenges with the app, by setting up a list of criteria for a goal within a certain time limit, and then challenging your friends to meet that goal, doing things like trying to get a certain number of head shots in Team Deathmatch, or whatever else you choose to set up. As I've said before, we've seen a few of these "game plus" apps, that supplement a console or traditional video game as you play it. But this definitely seems the most built-out version of this kind of thing yet. If you're a Halo player at all, you should definitely grab the Halo Waypoint app, free in the App Store right now.