You could also present examples of how skeptical thought is successful outside of the paranormal. Perhaps something about the process of cold fusion research and how skeptical thought led fairly rapidly to a demonstration that it was based on flawed research. The non-skeptics out there have since spent many many millions attempting to make it work with no success.
I'd also make it clear that skepticism doesn't mean not believing in anything; it means only being convinced by good evidence.
The homeopathic overdose is a good demonstration as well. You take an entire bottle/preparation of a homeopathic 'cure' all at once and show that it has absolutely no effect. The insomnia treatment is a good one, as you ought to be sleepy, at least, by the end of the talk if you do it near the beginning. Of course, this also requires you to talk about homeopathy, which may or may not be something you're interested in doing.
As far as how to present such a thing, I think that your best bet is going to be talking to your public libraries about presenting a lecture. They typically are more than happy to schedule an event of that sort, as long as the topic isn't anything inappropriate. Have a very clear idea of what you intend to do before you get there. Make sure that you get on any online calendar of events that they may have and ask about making fliers for your event (do you do it or do they?) You can probably get time at several branch locations, which should help you figure out what is and is not working in the presentation fairly quickly.
You might be able to get time at a college, but some have rules that the organization must be sponsored by a college group, so that's another layer you'd have to get through. If you are wondering about how to take your show on the road, you'd probably have to get a booking agent and charge admission; it's not a system that is likely to work though, honestly.
Another interesting place that you might be able to drum up an audience would be bookstores/coop grocery stores/coffee shops. Lots of these have times for presentations of some sort, and the audience you'd get there would be much more likely to actually need the skeptical talk than one in a library. It could be confrontational too, which would probably be more fun (at least it would be for me...)
