The Slackware Package Browser allows users to search for packages in the various Slackware trees. This means that the only packages you'll find here are the ones included in the official releases -- so no third party packages, sorry.
That said, what can the PB do for you? It allows to look for packages and
for filenames. Filename search is pretty usefull if you notice you are missing
some file on your system -- select the "file name" option in the search
form type in the name and ta-dam, you'll find the name of the package (or packages)
containing files matching your string! Simple, isn't it?
Actually, no! You are *strongly* encouraged to read the search tips
or your searches might return weird results, expecially if we are talking
about file names.