My personal Gentoo portage overlay; it contains stuff I need/like and which isn't in the official Gentoo portage tree. Plans are to submit as many of these upstream...
To use it with layman, add the following as a new file: /etc/layman/overlays/koh.xml
<repositories>
<repo quality="experimental" status="unofficial">
<name>koh</name>
<homepage>https://github.com/fbrausse/portage-overlay-koh</homepage>
<owner type="person">
<email>dev@karlchenofhell.org</email>
<name>Franz Brauße</name>
</owner>
<source type="git">https://github.com/fbrausse/portage-overlay-koh.git</source>
<source type="git">git://github.com/fbrausse/portage-overlay-koh.git</source>
<source type="git">git@github.com:fbrausse/portage-overlay-koh.git</source>
<feed>https://github.com/fbrausse/portage-overlay-koh/commits/master.atom</feed>
</repo>
</repositories>