Back in the day when I first started I didn't have much, an ez-curl bar and some plastic weights so I would do pushups. I would vary them, close grips, wide grips, deep wide grips using the ez-curl as a stand, incline(legs on high workhorse bench) and military pushups(handstand or legs propped high on the wall). I was young and grew like a weed but I would imagine it could still work now... especially now I know more about diet, rest, supplementation and etc.
-E