<p>I'm thinking of forming a <a href="http://www.catb.org/~esr/jargon/html/H/hacker.html" rel="nofollow noreferrer">Hacker</a>s Club at work.  My idea is that we would meet monthly and at each meeting one member would present an interesting hack he had created.  (The hacks presented wouldn't necessarily have to be software hacks; they could also be the sort of things you read about in <em>MAKE</em> magazine.) </p>

<p>There would also be <a href="http://www.catb.org/~esr/jargon/html/A/ANSI-standard-pizza.html" rel="nofollow noreferrer">ANSI standard pizza</a>, veggie pizza, and beer and pop available for socializing afterward.  I'm even thinking of calling the club "<a href="http://www.catb.org/~esr/jargon/html/T/TMRC.html" rel="nofollow noreferrer">TMRC</a>" even though it will have nothing to do with model railroads.</p>

<p>Has anyone ever tried doing something like this or have any advice?</p>

We do this at the office. I call it 'Developer Fight Club'
Usually do challenges of varying difficulty and compete against one another.
At the end of it, we go over our solutions, do code-reviews and discussions, and then use either benchmark results or other people as the deciding factor for who wins.
Typically, the loser has to buy lunch for the winner :)
For ideas of things to do, try stuff from
Top Coder
, programming questions on Stack Overflow, or even simple "
crackme
" applications available on different programming sites.
The main rules you'll need to adhere to are:
Make It Fun
Make It Educational Make
Make It Fair
Try to rotate the challenges, so either everyone is really good at the subject, equally bad, or at least mix it up often enough that it doesn't favor one person's skillset too much.