RPGGeek Virtuacon ’14 is taking place October 10-12th online and is a virtual convention open to all. They’re actively still soliciting GMs to run events, and there is prize support for GMs who take part. To sign up as a GM, you’ll need to have both an RPGGeek account and a G+ Account as Google Hangouts are being used for the games, join the G+ community for the convention, and follow a 9-step pitch for each game you want to run. The linked page also gives a list of games that are being pitched, so you can have an idea of what other people are running. There’s a wide variety of games listed already, including a great number of OSR games including B/X D&D, Castles & Crusades, and Star Frontiers.
The deadline to sign up is September 15th, 2014. Games can run On-Air at the option of the GM, but if they do, those taking part have to be 18+ and the games need to be marked Mature/18+.