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 has gone because a mod below the administrator gave me an infraction - despite the administrator personally agreeing to it.
If you need any php tips or tricks you can PM me.