+ 1 to burpees, I'm glad someone mentioned that.
Check out Crossfit.com for some training ideas - it will bring a refreshing new experience to you. Stringing together some bodyweight exercises will haul some serious ass.
Here's just a quick example, as devising these workouts are very simple, yet the possibilities are nearly endless.
Try a "21-15-9" workout, that is 21 reps off all 3 exercises, 15 of the exercises, and then 9. Keep a stopwatch to time yourself, and beat that time next week/two weeks from now.
21 Pushups, 21 Air Squats, 21 Burpees
15 Pushups, 15 Air Squats, 15 Burpees
9 Pushups, 9 Air Squats, 9 Burpees
If you bring the intensity, you will have one of the best workouts of your life, and I mean that with all integrity. Change up the exercises each time you do them, bringing new stimulus to your body each and every time. Maybe repeat a workout every 2-3 weeks, such as this one above, to gauge your progress. You could refer to a repeated workout like so as a "benchmark workout". Real fun stuff, always working to better yourself as an athlete.
By the time you get back into the gym, you will have some new abilities in you, which can bring some pretty great gains in the gym in terms of athleticism. Taking a break from the gym could be one of the best things for your training, you never know!