Most officially represented rpgs will be run by either Enforcers, recruited GMs (D&D Adventurer's League and Pelgrane Press will be recruiting), and other company representatives. If you are interested in running a one shot and looking for players, list the game here, when you will run it, how many players, and a description.
Think of this thread as a pre-con version of the LFG Arena.
Game: (The name of your game)
System: (What system you'll be using)
Description: (A short background blurb about the setting)
Date and Time: (When you want to run the game)
Location: (Where - I'm assuming RPG Dungeon)
Number of Players: (min and max players)