ohbrooke,
I have to agree with you. Just installed this plugin as well but was disappointed with it.
I forgot to insert client's name during my first creation of banner and I was unable to edit it now, worst still, I do not know how to delete that as well!
In my opinion, banner admin should allow you to:-
1. Add/Edit client
2. Manage specific group of banner ad under "one" client
3. Retrieve and edit list of banner by the specific client
Another important feature is that it should allow site owner to place more than one add per appearance. Having a html/text box which allow site owner to place table <table><td><tr>Ad-1</tr><tr>Ad-2</tr><tr>Ad-3</tr></td></table> is kinda convenient so you can place number of ads in the sidebar.
In joomla, they have a module called php module which allow you to do so. You can create as many php module as possible and place it anywhere by specifying the position.
Unfortunately, I am not a programmer, can't do that.