|PUBLIC SERVICE ANNOUNCEMENT (akkartik's idea)
If you're new here, don't get suckered by the outdated install instructions on this site. Use the community-maintained instructions at the arc wiki: http://sites.google.com/site/arclanguagewiki. Then come back here to ask us questions!
I try out different things in Arc sometimes, but mostly I just like to ponder it. My home languages are Groovy and Java, but I spend lots of my time learning new languages and thinking about language design.
...Hey, actually, that's not so accurate anymore. I've done a lot in Arc now, from Lathe (a collection of libraries which use a namespace system, which include iteration utilities and adventures in extensibility), to Penknife (an Arc-ish programming language built in Arc, with emphasis on generating code for other languages). Besides that, I also help out where I can with Arc implementations, giving bug reports and ranting about my own design opinions. ^_^
Some things I've done: http://www.rocketnia.com/ http://github.com/rocketnia
Some big ideas: http://rocketnia.wordpress.com/