Steam is having its annual summer sale at the moment and for anyone looking to replay any of the old gems there are opportunities to pick them up at a quite great discount. The original Quake literally goes for a couple of dollars and there's also the Quake collection featuring various games and missionpacks in the Quake series. The Steam summer sale started on June 22nd (i.e. yesterday) and lasts until July 5th.

Check out the Quake deals on Steam