I (finally) got Portal^TM yesterday, and I just beat it! ^_^

Also, one of the lines during the credits made me think that GLaDOS is going to be in the sequel (assuming there is one), despite what happened at the end of the game. O_o

Speaking of the sequel, I have an idea that could be used for it: A second set of portals. "How would this work?" you ask? Picture the "Infinite loop" maneuver. With a second set of portals, you would be able to turn a straight line into a circle: You fall into one that's on the floor, come out the other one that's on the floor, go back up through one on the ceiling, and then fall back into the first one.