I have started filling BOM (Bill Of Materials) database for Arduino related and other open hardware boards here - http://www.beeduino.org/bomdb/
My first aim is to get BOM for a few boards fully complete. Check at the same time how thing are going internally.
When working with new BOM, on the first step I do export partlist into a file (usually from Eagle design files). Second - the file is loaded into db and restructured (similar parts are grouped into one row) . Third step - additional info about earch part is assigned with searches for part in http://octopart.com
If you see some rows empty - then it is yet hard to me to find that particular part with full info in the sources that I said.
I am trying to gather info that seems could be helphul when you learning about new board even if you have assembled board or a full kit.
Are you agree? Any comments or suggestions would be greatly appreciated.