Per Joe I'm adding here. Activity is not always up-to-date, like maybe pushed out on some schedule?
It is a bit noisy for this purpose in that it writes a record for every operation. (edited, modified, answered, suggested, etc.)
Does not give up the originator ID and when posted time stamp
last reply time stamp missing,
number of replies would be helpful
no way to know; have I already read this?
What I'm describing is similar to MSDN/TechNet My Threads view. Activity may be useful for other purpose so maybe a new view is in order here.