Auto-disable connection in a low signal area

[Daved]

Is there any app that will automatically disable the data connection when you're in a low signal area?

It's very annoying to get network errors on the screen because the Apache wants to auto-connect to download my email (while it kills the battery because there's no signal)

I am sure I am not the first one with this problem... I just want it to not automatically connect when there's no enough signal for data.

Thanks