Seminar speakers--regardless of how famous they are or how many papers they've written on your favorite topics--are still just people who want to hear about your work, and help out if they can. Hopefully they conversation will flow naturally. But I still think it's worthwhile to prepare a bit before these meetings, and I recently found a perfect little template to help you do just that.
Joshua Goodman tweeted about a template he came up with to help his students describe their final projects in five minutes. I think it's excellent! What a great way to think about all of your projects!