So after much debate (OK it didn't take that much to convince me) I took up David's suggestion and ordered this book. I figured it's a good investment for me especially since I just took over management of the user group I've been with for a few years.
It's a nice short book - and while I haven't sat down to read it yet (I was @ Atlanta Code camp this weekend) I'm looking forward to it after having glanced through and already seen some interesting ideas.
If you're running a user group and looking for ideas, or thinking about starting a user group, I'd totally recommend picking up this book.