check up script/application

[moyashi]

wasn't sure which forum to post in but since I don't mind either -- I came here.

problem:

I saw somewhere or read somewhere of a script/application that checks if your sites/domains are up and running. (no, not on my own machine )

if there was an application with a nice gui great, but I be happy even with a simple script that is run through crontab.

hoping the functionality of this script/application would be to check a site, if running ... move on to next check. If down ... send email out complaining to sys-admin, me, hosting company.

any clues?