http://www.lorem-ipsum.info/generator3 - is handy for generating filler text when you are doing page layouts.
http://www.easyrgb.com/index.html - several tools here for color matching/choosing but it has an excellent tool for monitor calibration.
http://www.colorschemer.com/online.html - another color chooser I like
http://www.countrycodes.com/- this isn't webmaster related but handy to have bookmarked if you make frequent international phone calls.