Going through the top dozen people in Saints in our Book, merlyn is a famous wizard, chromatic has never explained his name to me, japhy just explained his name above, footpad's name comes from a game, davorg's name is a contraction of dave.org.uk, a domain he owns and turnstep is a piece of exercise equipment. The rest are apparently based on people's real names. vroom and tilly are last names, tye is a first name, and btrott and jcwren have prepended initials to their last names.

And so on. Generally it is pretty easy to guess where names come from.

BTW the one person whose name is real that I thought would have been made up is perrin. I would have guessed that he was named after the character in Jordan's series, but I would have been wrong.

UPDATE
I should mention that I know what chromatic means. I just have no idea why that word would have any special significance to chromatic. As opposed to, say, turnstep who I know is into aerobics.