Since I got online in 1995, I've began accruing lists and lists of websites to visit. Since the concept of bookmarks has been found useless, I've gotten in the habit of remembering useful websites -- not so much a habit, "repetition breeds familiarity". Besides the usual reference and search tools (like Wikipedia and Google), here are sites I think are worth remembering based strictly on my subjective perception of their use to me in the past years:
Paul Burke - Tons of useful material on computer graphics, geometry, some math, and topics of interest to graphically-inclined folks.
The good-looking textured light-sourced bouncy fun smart and stretchy page - Not updated very often, unfortunately. But it has proven to be incredibly inspirational and educational for graphically-inclined folks.
I'll try to update this list as I recover useful sites from my memory, which will happen by necessity. So this may not be updated very soon.
http://michal.guerquin.com/sites.html, updated 2007-01-20 01:01 EST