After writing rails_cron, and working with backgroundrb, I realized that I want something simpler. Much simpler. So I wrote the daemon_generator plugin. I think the whole thing is about 50 lines of code.

"./script/generate daemon <name>" gives you a simple stub that you can dump code in that will run in the rails environment as a background process. You're responsible for making it do something useful (try accessing stored tasks in a memcache or DB-based queue). If you want messaging, try backgroundrb.