I've tried swaret, but prefer slapt-get for its speed and ease of use:
http://software.jaos.org/
From the readme:
1. Features
slapt-get tries to emulate Debian's apt-get as closely as possible.
* uses native Slackware tools (installpkg, upgradepkg, and removepkg)
* supports multiple package sources (including linuxpackages.net)
* cache data concerning packages and updates from package sources
* supports sources from ftp, ftps, http, https, file:/// and more (libcurl)
* resumes broken downloads and will verify package integrity with MD5
checksum
* show packages that are available (from cached data) and installed
* search package listing using POSIX and extended regular expressions
by package name, location, and description
* retrieve, install, and remove packages by name or by specific version
* retrieve and apply updates
* upgrade from one slackware release to another in a few simple steps
* show description of packages, including mirror location, version, size,
dependencies (where available), conflicts (where available), description,
and installation status
* exclude (hold) packages from upgrades, by name or by regular expression
* transaction engine for install, remove, and upgrades
* "compare package version" algorithm to prevent downgrades
* recursive dependency resolution using slack-required metadata (see FAQ)
* package conflict resolution using slack-conflicts metadata (see FAQ)
* extremely fast and easy to script with