When viewing activity streams in condensed view, I think it'd be good to have the ability to expand individual entries to get more information on them.

That way you get the best of both worlds. The stream itself is condensed, but you can still quickly and easily get a summary of the individual entries that do interest you.

e.g., clicking the activity icon could expand/retract entries like so:

Then the "Condensed"/"Expanded" buttons could just be changed to "Condense/Collapse All" and "Expand All".

I like the idea.