Pkgusage lists all packages you have installed on your system with a number telling you how many days ago you last accessed any of the files in the package. Great stuff for cleaning out your hard drive.
Pkgusage supports RPMs, and Debian packages. Also, it is written to be easily portable to other package managers as well (contributions welcome ;-). Pkgusage requires a working Tcl installation. It is freely (re)distributable under the GNU GPL.