In an attempt to point to some of the great things that are available using Features, I tried to look for a directory of Feature Servers. Sadly, Google was not very helpful. After some digging, I was able to locate a page on the OpenAtrium Community site called Distributed Feature Servers. This points to many of the other pages I was able to find via search.
Utilmately I created a wiki page on the Packaging & Deployment group of groups.drupal.org, which seems to be one of the hottest places to discuss Features.
Currently, there is tons of info about how to create your own Features Server, but not much about where all the publicly available features servers are located. If you know of others, please go edit the wiki page on groups.drupal.org or leave them in the comments here.