It would be extremely helpful if we could make users with certain profiles believe they are deleting an object, while it is in fact simply made invisible for him/her and forwarded to a sysadmin for approval before it is either physically removed from the system, assigned to someone else or bounced back to the user.

This is because more often than not users do not bother to check if any critical data is still assigned to the record, such as activities or even opportunities, or they just don't care. A lot of my users would simply delete records because they are not relevant to them, even though they may be crucial to others, or because it's easy to get rid of lost opportunities by simply deleting the accounts they are linked to.