If you use Sprint PCS and have a plan that doesn't give you unlimited minutes, you may want to get a warning when you start to get close to your allocated time. I think Sprint has an add-on where they'll text message you your usage for a few bucks a month, but they give you the same information for free on their website. And so, I created a little script to log in and check that info for me, sending an e-mail if I'm over a certain threshold. See my weblog entry announcing it, and the script itself. (Of course, it's subject to breakage when Sprint changes their site structure, and you're on your own if it doesn't work for the way your particular minute usage is displayed.) I welcome any suggestions for improvement; someone out there may want to take the time to genericize it for other mobile providers, too.

Enjoy,
Silas