TimeIt! is an app for both Mac OSX 10.5 and 10.6 that enables you to quit an app you selected after the time you set has elapsed. You can customize the process by enabling plugins listed under "Additional Options", such as the download monitor feature. If you have a download running in Safari (Firefox will be added shortly), you can enter the file's filename, choose an action (available actions:Shutdown,Restart,Logout,Quit TimeIt! and Run Apple Script). If you choose the "Run Apple Script" option, you can tell TimeIt! to run the script once the download has completed, so you have endless possibilities of customized actions. Simply choose the *scpt (AppleScript) file in the options panel and the "Run Apple Script" option will be enabled.