Gentoo Overlays host ebuilds which are not (yet) in the main Portage tree of Gentoo Linux. Overlays therefore extend the pool of available ebuilds a big deal while integrating seamlessly with Portage.
The layman utility manages overlay subscriptions. Install it along with Git and Subversion as the actual ebuilds are hosted in repositories.
emerge -av layman git subversion
Now list available overlays and subscribe overlays you would like to use:
layman -L
layman -a {OVERLAY}
Please note that emerge --sync does not implicitly synchronize subscribed overlays as well. You have to do this with:
layman -S
The Sunrise Overlay contains user contributed ebuilds which are reviewed by Gentoo developers in order to ensure quality standards. We contribute to the following ebuilds:
The Ruby Overlay contains bleeding-edge ebuilds related to the Ruby programming language. We contribute documentation, do testing and contribute to ebuilds adapted for Gentoo Prefix.