Well, Slackware like most distributions comes with a wide range of packages. I think you should narrow down your question because basically with it you'll get a huge list of package names that won't be too much helpfull.
Answering your question, here's a package list with their descriptions:
ftp://ftp.scarlet.be/pub/slackware/s...e/PACKAGES.TXT
and here without descriptions:
ftp://ftp.scarlet.be/pub/slackware/s...ware/FILE_LIST