You only interested in upper body exercises or do I put weight on the 'improve overall work-out routine'?
Lunges, squats, (thighs, back side) Lunges with a sideways turn at the end (easier with a ball between your hands).
calf raises (calves) (on door step, stair, a big fat book)
the plank, sideways plank, (core, tummy, back)
jumping jacks going into a push-up when you come down, (cardio, core, arms)
sit on a chair, raise your legs from the floor, hold for 10 seconds (core, tummy)
grab on to edge of bed/sofa if it is stable, lower yourself towards the floor facing away from sofa, with arms behind you, then push yourself back up (arms)
Rope skipping (cardio, balance, feet)
Balancing on one foot with other foot raised in front, behind.... then try with your eyes closed.
Lie on tummy, raise upper half of body slowly off the ground, come down slowly...
Two buckets or big bottles of water will help with some of the arm exercises like curls, fly's etc
Getting a good resistance band would help the pecs, I think.
Also try push ups at a angle - perhaps on edge of sofa again, legs up, arms up...