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

WindowsNetworking: Product Review of PA Server Monitor: 5/5 stars!
TechRepublic: Considerations for choosing a network monitoring solution
Windows Server Monitoring Tools: A Server Monitor with Style
Microsoft TechNet
: Toolbox - New Products for IT Pros
NetworkWorld
: PA Server Monitor Pro: Straightforward server monitoring, with incredible power!
All Tech Radio Show
: April 19, 2009 (start listening at about 3 min 20 sec)
New York State Defenders Association
: PA Server Monitor being used by New York State Defenders Association
3D2F
: Server Control Tower