A German site dedicated to Netscape plugins that work with Linux . There are more of these than you might expect. Here is a user-recommended RPM Repository . Scientific Applications on Linux is an outstanding resource for anything even remotely science oriented. They list both commercial and free software, with descriptions of each.
Mirror sites all over the globe.
The Linux Applications and Utilities page seems to be a very complete listing of available software packages, with links to each package's home site. Their listing is hierarchical, and browsable. No searching capability. Check out the Linux Game Tome . They include sources, ratings, and screen shots.