Limiting Staff Access in MultiSite

Hello,

I was wondering how you guys at Edublogs.org limited the permissions of staff users. I am looking to add some helpers and want them to be able to make edits on client sites without me having to add each user to each site manually. I could make them super administrators but then I'd open a new can of problems.

Do you use a plugin for creating or limiting a particular user role?

Thanks so much!