Looking at Server, Application and Network Management ...

A relatively new territory to me for the most part.

The only big names that came to me are:
-Tivoli (now a part of IBM)
- Computer Associates Unicenter
- Nagios - Open Source!

Researching some more on some of the prominent players (as per the various internet search engines). In no particular order:
* Nagios
* ZenOSS
*Hyperic
* BixData
*GroundWorks

More on this topic to follow ...