mac version of registry?

Question for you from a non mac guy. One of my biggest pc gripes is that many programs add themselves to the startup process in the registry. I know this because my SpySweeper program tells me each time something like AOL IM, etc tries to set itself up to autorun on startup. After awhile it takes way too long for the computer to boot up becuase there's so much crap that tries to startup. This isn't really spyware, but its still annoying. Does this happen on a mac? If so is there a way to look up at the startup registry like a pc, and manually disable some startup processes if necessary? This is the kind of crap that makes a decent machine run slow. Very annoying.