I love to end my chest workout or arm workout with this simple push up set:

10 Regular Push Ups
10 Close Push Ups (tricepts)
10 Fingers pointed outward (bicepts)
10 Fingers pointed inward (tricepts)
10 Regular Push Ups

If you are away from the gym and just want to get a great arms/chest workout in, do this super set 5 times. (250 total push ups). If that is not challenging enough, do the super set 5 times, but make each exercise 20 reps.

Now drop down and give me 50!