Perf+ is an advanced free extension of perfmon with a tabbed interface and a set of predefined counters you can modify and share with others. Great for real time viewing of a host machine's stats quickly.
Still in the alpha stage, here's something I created to make it easier for me to find performance problems on servers. I decided to make this into a public tool so that everyone can benefit. The problem I had is that perfmon as a tool is not very usable. You need a lot of mouse clicking to get things done, and if you happen to, for example, change the instance of the application you are looking at, or use the same counters for a different machine, you're stuck with clicking the mouse a lot and removing and adding counters one by one. It's tough.
Because as part of my job, I also do lots of performance tuning and testing for enterprise applications, I needed something that will help me look at counters easily, because I usually have predefined counters for specific things I'm looking at (like trying to track down memory leak takes different counters than making sure you don't have too many connections open at the same time.
SO I built Perf+ to help me. This is an alpha version and thus not very stable, so I encourage you to submit bugs when they happen. It's free to download and use, so have fun!
The tool will stop working mid November by then you'll have to download a new version. I'm doing this to force myself to do monthly releases of my tools.