I mail users an edit-link for nodes with the node_authlink module. This works great.

But there's a small bug/inconsistency:
When you use the link to edit such a node and then save, you will see the node in display-mode.
Now there is still the tab to go into edit mode, but since the authkey is gone, it will fail...

So, either there should be no edit-tab after saving, or the authlink should be carried along after saving, so that the user can in deed go back to the edit tab.