The original home of this program appears to be BSD (together with 'jot' and 'lam'). There is a package for NetBSD, but the best version for Linux users seems to be the one packaged by the Athena people. Grab the source RPM and unpack it (with rpm -Uvh or unarc (/projects/unarc/)), you'll find a tarball which you can build with './configure; make' as normal. The spec files are Athena-specific so you probably don't want to rebuild the RPM itself.
An open, cross-platform journaling program.
A scientific plotting package.