Hack and Tell is a set of technology/language-agnostic lightning talks, except that they're all about projects you've built. You present for 5 minutes and then answer questions for 5 minutes.
As far as projects, most anything you've made is good. The rules are: no start-up pitches, no work projects , no deckware. You can read about the projects from previous meetups on github: https://github.com/danluu/madison-hack-and-tell
Please comment on this meetup if you'd like to speak. Don't worry about not being a good enough speaker; don't worry about your project not being polished/finished/cool enough.
: Let me clarify the "no job projects" rule. This rule is carried over from the original meetup in NYC, where they had problems with startup pitches and people wanting to talk about internal tools that are specific to the company they work for. General interest hardware/software/hacks are fine, even if they're work related.