FYI - Pingfarm will report success for all of your pings. However, since it's all done by your IP, you'll be blocked after 20-100 pings. You can fire up a javascript debugger and see that pingomatic reports 'slow down cowboy' but it displays 'success'.
Also, you guys shouldn't do RSS feeds any longer. We noticed a negative correlation happening when submitting RSS feeds with our pings. That's why we took them out completely.
I'm not aware of a reliable pinger that is free.