cron-job to move inactive users

[pyd]

I would like to have a cron-job that does this:

Every night it scans for users who haven't logged on for x (ex. 14) days.
These users should receive a email to ask them to come back!

Every night it scans for users who haven't logged on for x (ex. 23) days.
These users should receive a email that tells them that they will be marked as inaktive members if they don't log on in x (ex. 30) days.

Every night it scans for users who haven't logged on for x (ex. 30) days.
These users should be moved to a specified usergroup

Is this something that someone would be interested in creating?
I think it would be greatly popular!