I do as much as I possibly can. I used to go under Shane Prower, but now my real name just cuts it for me. KrissuKun and I are currently working on a project together (he used to post at SAGE whereas I had stuff on a personal website) but its not going to be revealed until it's finished. We're building it from scratch, using a static engine I toyed around with a year ago or so. When release info about that is out, you'll know. After that, I hope to making some healthy contributions to this community... hope to. As I said, everything I do WILL be open source, so...
Also, I'm currently working with A.J. Freda on the SRB2 soundtrack. If anyone is interested in that, I'll post links once he's heard. I also will do any other music stuff for anyone who requests it. Right now, SRB2 is my primary project to work on. Everything I do musically is free unless anyone I'm in a band with whines for it to be otherwise.
I've worked with TGF, MMF and their "sequels", I used Game Maker 4 a LONG time ago, and could probably pick it up again, and have messed with Mode7 and (VERY LITTLE) C. I used to do spriting and am currently making a spritesheet of myself (woo) to put for cameos in games. As I recall, this community used to be pretty big on that stuff. I have Photoshop and have had it for a while, enough said.
When I have something to show off, I'll post it. I'm generally a nice guy unless you come off as a jerk... So that's me for those of you who cared.
On Topic:
As for open source; like the others said, if anyone tries to steal it, the source is usually easily tracable. If the guys like you mentioned got caught, they obviously don't get too far with it, right?