If you are looking for packages that are not included in a SUSE distribution, you may find packages that have been prepared for Red Hat or Fedora rather than for SUSE. In some cases this will not be an issue: they will install by rpm without problems. In other cases you may need to install them with the rpm options -nodeps and/or -force; they may then run correctly, but might not. It's certainly well worth looking for packages built for SUSE first. Good sources for these include the following:
If you want to install Debian packages, that is also possible-the package alien allows conversion of Debian packages to RPM format. Again, there are no guarantees here: some packages will convert, install, and run perfectly, while others will cause problems. It is also possible to install the package deb, which contains the Debian package management tools and allows you to install Debian packages natively using dpkg. In general, this is a bad idea unless you have a very good reason for it and know exactly what you are doing; if you run two package managers in parallel, neither of them can have a full knowledge of the overall state of the system.
You may, however, want to use the Debian package commands with rpm. This is possible on SUSE Professional if you download the apt4rpm package. Repositories of SUSE packages designed to work with apt4rpm are available and more information can be found at http://linux01.gwdg.de/apt4rpm/home.html.
Also of interest is the fou4s project, "Fast Online Update for SuSE," which can be found at http://fou4s.gaugusch.at/. This provides an alternative lightweight interface to the functionality of the YOU, with certain additional features including the ability to access third-party packages from some of the sources listed in this appendix.