I have just inherited a relatively poorly written application in a new job. I am going to take pride in optimizing it so the pages load in less than a second (some are timing out when there are other users on the system), clean up the crappy bits and make it more maintainable.

Sure its no as nice as getting to architect a whole application from the ground up. But the database seems well designed, so it shouldn't bee to much problem to make it faster and prettier and cleaner code.