I've been looking for a good starter project to get my feet wet with Arduino. I came a cross an article on make where a guy mounted a switch on his mailbox and he received a text whenever the door was opened.
Here is the link
http://blog.makezine.com/2010/12/29/snail-mail-push-alerts/I'm not quite sure how to trigger it with mach but it shouldn't be too difficult. I'm also thinking that with an additional output and a macro I could get a notification when it's done running. A power failure indicator would be nice as well.
I do a lot of 3d work and I run the machine 24/7 if necessary so an estop or power failure can cost me 12 hours or more depending on when it happens.
Any thoughts
Derek