In Activity Streams, verbs are their own objects, and the variety of actions that can be represented is limited only by the standard itself. Providers can also use verbs outside the standard, taking the chance that they'll eventually be incorporated, or that a downstream client could parse them anyway. Here's a list of the verbs incorporated in the Activity Streams standard so far:
The challenge for Friendfeed and the like is that while I really like all my services gathered in one place, I would rather that these would be centralized on my blog instead of a third party service. Yes you can cross post or add badges, but it's not rea