Things have a funny way of coming together in a user group. At our last meeting, there was a question about converting RGB values to hexadecimal numbers (or it might have been the other way around). I said that a search online would probably show some kind of converter, but I was not aware of one off-hand.
Here's where it comes together: This particular page about Bookmarklets - Design tools has some web design bookmarklets, and one of them is a converter for RGB values to Hex and vice versa. Try it out--it's a nice tool to have.