parts.reprap.org died the death of bitrotting. D'oh.
In the days when RepRap moved from the very first printer design, Darwin to the Original Mendel, one of the (back then) RepRap key guys, Zach Smith (now Makerbot), set up this site which contained a quite nice parts managing system. Today, the owner of the server in unknown (it's not the same server which runs reprap.org), so this wiki page was created to archive it's contents.
Where's the data?
How to find the part I need?
Open either the Google spreadsheet or the backup of it and watch out for table tabs. The first tabs list all parts, countries and such stuff. After that you'll find a table dedicated to each piece of electronics. Review a parts' name in the list with all parts to find vendors.
Extra bonus if you bring the result of this simple research into a table on the wiki page pointing to the data!
How did parts.reprap.org work?
As of this writing, the About page of parts.reprap.org still works and describes many of the internals nicely. In case it stops doing so, see a pixel-exact copy of it in the picture below. The links mentioned there match the ones given above.