Moz has begun Add-On Collections (via Ajaxian</a/>):

Today, we’re excited to introduce a new feature to our website that will expose the niche add-ons that can be hard to find, and gives users a more active role in helping outstanding add-ons bubble to the top. One thing we’ve learned as add-ons have grown in popularity over the years is that once a user finds an add-on they love, they become a fan for life. We see this all the time as people recommend add-ons to their friends and write great reviews. And we’re very happy to see so many bloggers writing about lists of their favorite add-ons.

Now this is interesting for a couple of reasons. Firstly, it’s an example of the URL Trail pattern; Firefox Collections is a framework allowing people to publish and share a collection of links; very similar to Amazon’s “So you want to …” ListMania. It adds the ability to do something that neither I, nor Vannevar B. mentioned about trails: the ability to subscribe to a trail, in order to see changes made, e.g. Here is the RSS feed for the Social Circuit collection.

The second hotness about Collections is the fact that Firefox add-on management is getting easier. You can click on a bunch of add-ons, like adding them to a shop cart, and install them all in one go:

It takes Firefox closer to where it should be IMO, in which add-ons are easily installed with one click, and distros are available for specialised needs, e.g. a developer build containing Firebug and other dev tools. Moz themselves might be wary of blessing certain extensions in this way; so the ideal situation might be if they were to provide a framework like Collections, where anyone can propose a bundle and the best bundles rise to the top, with a way to yoink a Firefox build containing all the add-ons in a collection.