i have bought the nexus for one month. and the machine is very quickly and without any problems. then sharing my experience.
Since many software needs root permissions to run. And in order that we can better manage mobile phone, you can flash roms to get root privileges,you can download roms here http://forum.xda-developers.com/forumdisplay.php?f=559
android is an open platform-wide, so there are a lot of software related to all aspects of the application for nexus one, you can go here to download, http://www.androidfreeware.org/
In order to personalize our phones, we must download a variety of personalized mobile phone ring tones, pictures and themes, here an excellent resource for mobile phone download site, http://www.mobicomet.com