I'm also now seriously thinking about joining the slashcode mailing list. Just to see how it goes. If I like the atmosphere, then take at look at the code, learn perl, and maybe start hacking away. I really can't complain too much about slashdot mechanics if I don't try something myself.
The only mailing list I'm really on is that Open Source book on Open Source. It's really boring. There's no clear direction and the enthuasism has died out. I'd guess that the mose enthusiastic are Ps, the very same that don't want a design of the book before it starts. Once the enthusaism dies, though, so does their contributions. The Js want more direction, and are slower to get involved, but stay for the long run. Both skills are needed, but it looks like it was all P and no J. Some chapters are being written, but the mailing list is pretty silent. I wonder if the book even has a chance.