Ok, so you don’t have any friends to add to your Twitter: how about your server? :
if you think Twitter is all about personal micro-blogging and basically a waste of time, think again. with their recent API-extension, it’s now possible to integrate Twitter as a cost-free SMS gateway into your own applications (like the guys at Tupalo have already done).
of course there are loads of SMS-based monitoring services out there, but the good ones aren’t free, and most aren’t very customizable. my simple demo PHP-script monitors any number of web-servers and alerts me by direct SMS if one of them goes down. just insert you account-credentials and make it a 5min-cronjob. keep in mind that you’ll need two Twitter-accounts for this kind of application, with the sending-account added as a friend to the receiver. otherwise the script can be easily customized and extended for you own needs…have fun!
ps: it might be a good idea to simultaneously run the script on two independent machines on different locations!