A smartphone is actually a powerful GPS golf tracker. With the Foursum app, you can see the distance to the hole and even use a swing analyzer (since the app tracks ball placement). There are 21,000 courses included. You can keep score as you play, but most importantly, the app makes club suggestions based on distance and info from other users. During a round, you can also follow other nearby golfers and see their progress. The app works a bit like Foursquare in that you can earn badges like most rounds or best birdie streak. Foursum also shows leaderboards for that course – which might be a little depressing. Coming out soon for both iOS and Android devices, Foursum is currently in beta, which means you'll have to sign up and request an invite first on the Foursum site. [Free beta; foursum.com]