Archon ---> Quake. You heard right, elements of the 80's micro game archon extrapolated into the Quake universe. Get ready for a wild ride. (free stuff | no warranty | see disclaimer.txt | blah blah blah.)
A short viddy of the pk cube in action. Simple - walk up to the cube and touch it. Then (if you are in range) hit your fire button and it opens. Hopefully giving you a goody, like the gravity well bomb shown here. This new element will be featured in PK 3.0 and Archon.