In neetoCRM, we track inactive leads and deals. Activity such as tasks, notes, attachments, mail, SMS can be performed on a lead/deal. neetoCRM stores the time of the latest activity performed on a lead/deal.
Now you can view a list of leads/deals which are inactive for "X" days. By default, 30 days are considered for showing leads/deals in this list. But this can be configured on
Settings->General->Configure->Inactive Days.Here you can add the number of days for which leads/deals with no activities would be marked inactive.
In the menubar on the leads/deals list page, No activity > x days option is added to show these leads/deals.