Came accross this really interesting flash presentation (click on the "Imagining the Tenth Dimension" link on the side) that takes you on a step by step tour through imagining the numerous dimensions (some say up to 11) of the world offered by String Theory.
This is one of the best presentations of ways to visualize 4, 5, and 6 dimensional space. Of course, it goes all the way up to 10th dimensional, but at that point my brain goes "plop."
I especially liked the part that draws a parallel between how we perciever time (as if it flows from a time a to a time b) to how a "flatlander" would perciever a three dimensional object (as if it moves from one cross section to the next). The implication from this is that if we could exist in 5th dimensional space, we could see the 4 dimensional object and therefore see all of time. Psychic implications, anyone? If not, still very cool.
Check out the presentation. This is why I love physics. I'd forgotten why at one point I wanted to go into string theory. Cool shit like this. Yeah!