Ya know, I just had an idea for a Portal spin-off game. One where you run the enrichment center as GLaDOS. You can create your own cores, and try to keep them happy, run tests to earn new stuff, and maybe try to catch Rattman.
Haha yeah I've seen people on some other forums I frequent that say Valve needs to make a Sim Aperture game where you play as GLaDOS and build on the facility.
see my portal personality core series for more info...