MIT's Drew Endy has some good insight into how to give worthwhile group meeting presentations, "though it is clear that this is useful advice for any presentation," says PhilipJ at Biocurious. The foundation of a good presentation includes saying what you are going to talk about, telling your audience why it matters, and letting the group know what you want or need. It's also good to remember that your audience is comprised of three types: the supernerds, the lost, and the dozers.