I'm sure other admins out there would find this useful, especially if, like me, you have to manage a high number of OUs, or if your Organisation is based on location. (Simply, our users are spread around a number of countries, so we have a User/Country/Organization hierarchical structure. Actually, it's a little more complicated than that in our case - but for the purposes of this post... ;-)
My idea? Have a way of emailing everyone within an OU.
Currently, you can use wildcards (*/OU/O) to allow access to a Notes resource, but you cannot email such a group - I think you can in Exchange ;-) !
This would certainly come in handy for many admins, and would save a lot of hastle when it comes to group management.
There are other features that I would like relating to OUs but this is a great place to start!