I have attended the Ottawa Group of Ruby Enthusiasts (http://ottawaruby.ca/) for about a year now. It has been a great place to meet other Ruby developers and learn interesting things.
The group normally has a main speaker who gives a long talk and one or two 10 minute lightning talks punctuated by breaks to eat pizza and talk. The main talk is normally over Skype and the lightning talks are done by volunteers from the group.
I have given two lightning talks on topics which I believed I might know more than other members. Both talks went well and I’ve decided to post the slides. Be aware that I did do a significant amount of talking so you can’t get the whole message from just the slides, but they are better than nothing.
I recently did a full length talk on the Ruby standard library. You can find the slides at http://thume.ca/rubytour.
The first talk I did was on writing programming contests in Ruby. I write lots of programming contests and have tried using a couple different languages for them but keep coming back to Ruby.
My most recent talk which I gave last meeting was on using Ruby as a scripting language to automate repetetive tasks.
I live coded a simple Ruby gem using Bundler in 20 minutes and explained some tricks and how easy it was to write Ruby Gems.
I recently gave an improvised lightning talk prompted by the lack of other lighting talks called “How to do a lightning talk.” I talked about choosing a topic that you feel you have unique knowledge of to give you more confidence and how all that was really important was the confidence to go up there. Everything else would work itself out.