The first three games in the Quake series are currently 60% off in the GOG (formerly Good Old Games) store, which may be a good opportunity for anyone who haven't paid their Quake taxes to Shub-Niggurath just yet.

For QuakeWorld in particular it's of interest as the popular nQuake package is based on the Shareware version of the game, leaving players with the deathmatch maps and the first episode of the singleplayer part of Quake. If one should buy the game off of GOG (or Steam etc) then one can copy pak1.pak into /nquake/id1/ for a complete version of the game.

More info on the deals at Reddit