/dev/random for Solaris
It's equally handy for OpenSSH 2.x, because the built-in PRNG can be very slow, and may need to be custom-crafted depending on where you put your log files, etc.
This will be handy for OpenSSH 1.2.x, as the Sun /dev/random is only available to customers who have support contracts.
OpenSSH 2.x has a built in entropy gathering functionality, which should help for running OpenSSH under Solaris.
An open, cross-platform journaling program.
A scientific plotting package.