
Dorkbot meetings [a.k.a DorkFest] typically involve presentations by people from diverse backgrounds - from engineers and computer scientists to artists and musicians, followed by open discussions. Meetings are free and open to the public.
Dorkbot meetings are also about networking, getting inspired by other peoples work and giving people a possibility to introduce their work in a public venue.
Word of caution: demos of commercial software are not appropriate, unless you wrote the software or you are making it do something particularly novel or interesting.
Interesting Dorkbot find - Here's an electical model illustrating a Mind have a Will but capable on only two ideas:

Start a Dorkbot group in your city
More on Dorkbot Meetings @ NYTimes and Yahoo!