Go4Launch allows you to easily add startup tasks to OS X using launchd services! Go4Launch does all the behind-the-scenes work and creates a "template" shell script that you can modify (e.g., sudo vi /Library/BootScripts/go4launch.sh). Add your own commands to the shell script, save, and you're done! If you're looking for a more robust solution for managing launchd services, we recommend Lingon. This is a very simple app, perfect for do-it-yourselfers.