iOS: Workout buddies are a great source of motivation, whether they're at the gym with you or keeping in touch from afar. A new app, ACTIVEx, lets you create goal-oriented groups with friends or strangers, and even has a button to whip up a quick group workout. The groups, called "packs", stem from Active.com's employee fitness program. Once you've joined a pack, you and the other members can schedule group workouts. You can also motivate or trash-talk each other on the pack's home screen.
Some of the app's other features don't make as much sense for a global fitness community as they did for Active's employees. For example, a "commitment wall" of people who have signed up to run a 5K is a cute idea when it's a bulletin board of co-workers, but just a bit of randomness when it's a screen in the app showing the faces and names of strangers.
Still, the app is a fun addition to group workouts. Training plans are available for $5.99/month, but you can use the Tabata Builder for free. Just punch in the number of people (this works solo or with friends), and tell the app what kind of equipment you have available. You'll get a surprise workout with a bodyweight warmup segment, followed by a series of short but intense interval exercises geared for your group.