Time spent in each status such as Online: 3h 42m Out to lunch: 0h 34m Away: 7h 47m etc...
Time that the status's change
Sign in and sign out times
Counts on how many times they sign in / out... how many times they switch to each status (as they click away, add 1 to the count)
This could also include filters, say only show people from Family group, or only show people from Friends & Enemies groups. I think it would be something similar to Microsoft Excel Pivot Tables.
also it should record yourself... and graph the results showing yourself compared to your friends.
Obviously it will start small and over time get bigger and better with more advanced graphing and filtering but it would be a popular plugin as we have seen from the votes
Jay