Game/Writing
Pretty much all of the stuff I've done to date has been for various permutations of the d20 system. I play other systems, such as Deadlands and Exalted (as well as other Storyteller games), but most of my game writing and the majority of my playing is d20 based.
I've actually been writing and playing d20/3rd Edition Dungeons and Dragons for slightly longer than it's been commercially available. I managed to work my way onto the initial pre-release list of outside developers run by the inestimable Ryan Dancey several months before 3rd edition actually hit the shelves
Stuff I've Written
My first actual sale was to Atlas Games, for their En Route collection of encounters. It was so cool to actually be published. My contribution was a short encounter called "Dance The Night Away", revolving around tricksy pixies.
My second was to Bastion Press, for their Spells and Magic sourcebook.