Pushups work the front. If you work the front and not the back, you can get a muscle imbalance. That makes your shoulders sore and can lead to bigger problems.
Get a tubing set (latex tubing with handles and a little doohickey to put them on a door).
This is what I do on arm day. Face pulls/bent over reverse flye/one arm row/and a variety of shoulder exercises that come from the PT world, but work.
I absolutely love this one, and do it more than I should. You can keep putting your feet further away from the wall to increase resistance. Takes a couple tries to get it right. But if you do, you'll like it.
Cycling also works the front, and it helps to balance that out by working the backside, the fancy term for that is posterior chain.
Couple really good exercises for that are deadlifts (you can stand on the tubes and use them for resistance) and one leg RDL.