Sometimes you might be in a sticky situation where you know a filename, directory or path, but would like to know which package installed it or can be installed to obtain it.
The apt-file program is your savior for this situation. Use its search option to find the packages which contain the filename you are looking for. If this program is not present, it can be installed from the Ubuntu repositories.
For example, to find which packages have a filename with Foo in it:
$ apt-file search Foo
Tried with: Ubuntu 12.04.1 LTS