Where Do I Come From?
wheredoicomefrom is a (potentially useful) tool for anyone using a debian-like system (such as Ubuntu). You tell it a file, and it tells you what package (if any) was responsible for putting the file there. If it isn't installed by any packages, then it tells you so. It is a pretty simple application, it just reads through all the files in /var/lib/dpkg/info to see which package installed it. But, I can actually imagine this being useful.
Get the public domain ruby source.

RSS
dpkg -S file
instead?