You want to listen to music your friend has, but you don't want to listen to what they're listening to right now
- Right-clicking on their avatar (or some other mechanism) gives you the option "Browse their music" (if they have serving turned on), which points your music player (Rhythmbox, Banshee, etc.) to their server, giving you a list of songs.
You want to listen to some music your friend is listening to right now
- Same as above, but the option is "Listen to their music" which points your music player to their server, and synchronizes your music selection to what they're listening to at the time.
- The main point of this is to let your friend act as a DJ, when you want to check out music they're into
You want to view a web clip your friend has viewed
- Maintain a list of web clips (where the the URL is the URL of the page that embeds them) viewed
- Like the audio cases above, right-clicking on their avatar (or another mechanism) lets you browse recent video clips
You want to view a web clip your friend is currently watching
- A similar mechanism to view the web clip that was visible on their screen most recently (ie, what they're viewing now, but focusing other windows/changing desktops doesn't nullify "currently watching")
- needs to scrub out ads and other junk that are the same format as regular web clips
FIXME: add cases for personal photos, videos, other content (which is meant to be public, also what is meant to be shared just among friends)