Here's another color palette generator I discovered recently: ColorSchemer-Online-v2.
What I like about this one is that it quickly creates a palette of 16 compatible colors. It doesn't give the fine control of some of the other color generators out there, but for my beginning level kids, this is a good place to start. Enter a hex code or the RGB numbers, press a button and "wal-lah", instant pallette.
[Image: Captured from http://www.colorschemer.com/online.html]