So I decide to try a community created ROM on my Nexus One and I went with the CyanogenMod (http://www.cyanogenmod.com/) because it appears to be the most popular. I have not found any good documentation which tells me what apps are included with it and what the purpose of the app is. So I am going through it listing the Apps and links to some documentation. Here we go:
ADWLauncher.apk - http://jbthemes.com/anderweb/adw-launcher/adw-launcher-information/
This app replaces the Android Launcher which is the little bar at the bottom of the screen and gives you access to the apps drawer. What is nice about the ADWLauncher is you can customize what other apps are on the bar by simple dragging and dropping them onto the bar over the existing app shortcut that is there.
Needed to prevent force close when accessing CyanogenMod Settings
CM Parts Helper
DSPManager.apk - http://bel.fi/~alankila/android-dsp/
This is a base system framework update, which gives enhanced sound processing capabilities to 2.2-based phones.
RomManager.apk - http://www.koushikdutta.com/2010/02/clockwork-recovery-image.html
ROM Manager is a Android front end to the Clockwork Recovery image.
Extra 'settings' menu
Sim Tool Kit; manages multiple SIM cards
There are a few other apps but they don't need much explanation. I also found this page on the CyanogenMod Wiki which has a good list http://wiki.cyanogenmod.com/index.php?title=Barebones. Overall I'm happy with the CyanogenMod and look forward to new versions.