I've had people tell me pushups are an endurance exercise and to do them every day. One example I got was to bang out 10-20 every time I go to the bathroom, if you drink alot of water...well, you know.
I haven't tried it yet, so we'll see. I was also wandering around online trying to find info on this very subject. I read some stuff on a couple of forums, I'll see if I can find links. However, most of these people aren't cyclists either, so your needs are probably a little different from theirs.
Edit: Here's one of the links to a forum I was checking out. These are mostly LE/Military people, so take what you need and discard the rest
http://www.911jobforums.com/vB/showthread.php3?t=36578