How to start a service automatically after openning an application? For example, I have a service that I want it to be started automatically when I open Firefox.

I know how to write scripts as services in automator, but I don't know how to make a hook that when Firefox is openned, it started the service.

Does anyone have ideas about this? Thanks!
Besides starting both programs via a script as you told I can only think of Keyboard Maestro which is a powerful macro program for Mac OS X Mountain Lion, Lion and Snow Leopard.  

You can do a lot of crazy stuff with it. And you can trigger macros when programs are running or not running which is what you want.