The Management Center's resource library
They've got sample scripts for difficult employee conversations, worksheets designed to help you plan projects, the best list of reference-checking questions you'll ever encounter, sample rejection emails, and much, much more.
(Note: You need to sign up for their free monthly email list in order to get access to the library. But their email list is also ridiculously useful, so don't be deterred by that.)
The Management Center is near and dear to my heart: It's run by Jerry Hauser, my co-author on Managing to Change the World, and they're obsessed with helping nonprofits become more effective, an obsession that I share. And they're great at what they do. Also, one time they bought me a small pie.
You should get to know them. Go download all their free tools and then spread the word.