As I am working and managing several gentoo boxes, my local portage overlay was the most annoying thing as it was never in sync. So my solution is setting up my own subversion repository containing my ebuilds to distribute them via layman on my boxes.
To make use of the repository using layman, you need to add my Overlay-Listing to your layman.cfg file. Then ask me for a username and password. Typing layman -a stargazers should take care of the rest.
Now what’s in that repository? Well, various stuff, as some iwlwifi ebuilds to be used with the mac80211 subsystem emerged from separate ebuilds and some other version bumps and fixes