I second what the last poster said, about concentric movements. S-L-O-W push-ups really help a lot. I got it to where I was doing 6 to failure--literally, 30 seconds or more per push-up. It does not feel good, but it works quite well.
Another thing I'll throw at you, something a friend did. He wanted to beef up on the cheap, so he went and found a couple big 2x4 piece of lumber and kept them in his apt. Every day, he would just walk around in the apt. for several minutes carrying those pieces of wood until his arms got really tired. Our female friends have all been saying that he needs to stop, because he's getting too big. I think he does about 200 push-ups a day, too, like you.