Plisterine is an application that will help you easily create launch agents.
What are launch agents, you ask? Launch agents are magic little files with which you can automate the launching/running of applications and scripts when certain conditions you define are met.
With Plisterine you can create launch agents that: launch an application/script: at a specific time every day at a specific time on a specific day of the week at load or login when a change occurs in a folder (file added/deleted/moved, etc.) when a new volume or disk is mounted or that run an application: all the time (and automatically relaunch it if the application crashes) on an interval, such as every 10 seconds or every hour relaunch only after a crash (as opposed to properly quitting)