And, have you seen this step-by-step guide in HBR for improving conference diversity by Sarah Milstein? She used to run Web 2.0 and then Lean Startup.
I tried the advice in Sarah’s post more generally just for regular startup hiring and it’s genius. Really easy to put in place things that work and, as a pleasant surprise, I almost always find that recruiting people that aren’t normally heavily recruited ends up with someone who works harder and is more reliable. I’m sure you’ve had plenty of speakers who didn’t bother to work on their talk until the last minute — those are the ones you’re going to end up replacing with this process you’re putting in place.