There is now a way to filter contacts based on how recently they have been active!
This is great for cleaning out your list of people who haven't interacted in a long time. For example, you could filter for people who have been inactive for at least 90 days, or 180 days, or whatever time frame you'd like. If you want to see those who have been active in the last number of days, click the "Active" radio button above the field where you type in a number.
Please watch this short (5 second) video it will show where this field is. To get to this filter box, go to the Contacts menu, click Manage, then click the Filters button and this will appear.