Exherbo (2007—present) is a source-based [Li|U]nix distribution. Like Gentoo, another popular source-based distribution, Exherbo emphasizes installation of system software — from kernels and kernelland services to users and userland applications — via local compilation. Local compilation compiles software used by a system on the system itself. Systems for which a majority of the software is compiled in this manner are source-based systems. Distributions producing such systems are source-based distributions. Exherbo is one such distribution.
Source-based systems tend to perform optimally with respect to conventional systems. In these systems, the software used by the system is typically compiled elsewhere (e.g., by someone else having some other system).
See Gentoo for poetic diatribes on source-based distributions, and more details in general.
Leyli Cecil, the maintainer of Raiazome, also maintains third-party Exherbo repositories. These are:
See the README accompanying each repository for installation instructions — and thanks.