H&&T (http://hackandtell.org/) is a show and tell style meetup for hackers!
Events are structured such that 3—10 programmers give 5 minute long presentations on something they've built, followed by a 5-minute Q&A. After the event there is a break to hang out and mingle with other presenters and participants.
Presentations of almost any kind of tool, hack, library (did you just write a library to access the Meetup API in Haskell?!), whatever, are encouraged. We're language/software/hardware agnostic, so it's all fair game. However, we do not allow 1) startup pitches or 2) work projects.
We want to promote the projects that people do in their spare time, for fun, or utility, and not the kinds of projects that are only applicable to people who work in your company, or your direct clients. On the other hand, there may be a project that you've built primarily at work, that solves a *general* problem that your company has allowed you to release with a libre license -- this is usually fine.
Our mailing list has a strict no recruiters and no promotion of commercial projects policy. If you think that your message to the list might not be appropriate, either run it by the organizers, or don't send it!
Leo, Marko, Miriam, Satabdi