[CentOS] Monitoring services

What's available to remotely monitor services? What I'd like is something 
that can run scripts for each service to connect to a port and verify that 
it's up, and then send me an SMS message (phone text) to let me know which, 
if any, are down.

Also, does a script exist that checks all the services listed by chkconfig 
and reports those that should be up but are down?