monitoring internet availability and sending sms alert?

[Adam Hardy <adam.ant@cyberspaceroad.com>]

I figure this is probably something I would have to script myself because I 
can't find anything useful looking out there, but I thought I'd ask before I try 
(or perhaps before I procrastinate again):

I have a machine here at home running some 24x5 programs which I really need to 
keep up and running, along with my broadband so it can get its datafeeds.

I figured I could run a program on my webserver to ping my home machine 
regularly and in case it starts to slow down, lose packets or die completely, it 
could send me an SMS to alert me to the fact.

Is there something like this already in existence?

Thanks
Adam