A few product mentions that we've come across...

“After testing almost 20 monitors in the market from free to thousands in price tag, some too hard to maintain, most yielding too many false positives, we found peace with PA Server Monitor. Adding the prompt support into the stew makes one feel like having a real "IT Gourmet" on the plate for the price of a hamburger. Now I can forget about the servers on my spare time and wake up well rested in the morning knowing no SMS = no problem.”