PHP should do the job. Infact to be honest, any language that can pull a webpage will do it. The thing is though, PHP is passive in the fact that it only does anything (by default) when you activate it via a http request. Other languages will compile a program that 'runs' constantly. You can do this with php too but webservers (especially shared servers) don't typically allow a user to do this. You could however use a cron job to trigger a script every few minutes.
My helpful sig is on vacation trying to loose some weight. It got a bit fat and caused a few problems but it will be back at some point!