I'm planning to include some live call-in programming, and around this island that could prove a little risky-- so I've been looking around for a cost effective way to maintain control of what goes out on the air, and I think I just stumbled across some free software to do it!
It's called "Radio Delay", and while it's actually designed for syncing a radio to a tv tuner card in your pc, it does appear that it can just as easily, and effectively serve the function of a profanity delay for broadcast. It can delay up to 30 seconds, its a tiny program (178k), and it works in XP or Vista (no mention of a mac version).
Now I've only read over the tutorial and looked at a few screen shots so far, but it looks pretty cut and dry to me.
Check it out!: http://www.daansystems.com/radiodelay/