Previously, in Eloqua, we were able to see user login reports. It showed you hours they log per week/month in Marketo. This report helped a few ways:
1) Allowed me to remove inactive sales/exec accounts
2) Easily identify power users
3) Quiet complainers/problem users who spend very little time in product
I'm sure there are other use-cases we could find, but it would be nice to see this feature added.