With the move to Firefox 3.5 we now have firefox collections. This nicely solves a regular problem I always had; referring a good set of extensions to someone who has just moved to firefox or is not using extensions yet (yeah, people do that).
I used to collect a tagged list of extensions on my delicious pages that people could scroll over to pickup from. It also helped my selectively pickup extensions on new browser installations around the place.
I can now quickly refer people to my extension collection to which they can subscribe and get updates as I post new extensions or edit out any old ones.