rpm-depend can easily find packages fitting the capabilities required by a given package. It works only on directories with RPMs like mounted media for now. RPMs in a given directory are recorded in caches to enable quick lookup on the next query. It includes the ability to omit packages installed in the current system (i.e. list only missing packages) and resolve package dependencies recursively (i.e. if A depends on B, resolve B's dependencies as well).
yumpkgs is a tool to help people download the right set of RPM packages needed to update another computer that can't download the packages itself, for whatever reason. After the packages have been downloaded, they can be transferred to the other computer by way of a flash drive or portable disc. yumpkgs produces a list (downloads.list) with a .bat script that can be run on Windows to do the downloading.
Package Converter is an alien frontend . Alien is a program that converts between Red Hat RPM, Debian deb, Stampede slp, Slackware tgz, and Solaris pkg file formats. If you want to use a package from another Linux distribution than the one you have installed on your system, you can use alien to convert it to your preferred package format and install it. It also supports LSB packages.