www.brainbench.com
They have paid ones and they offer a free few ones... if you join the site you will get emails every now and then that tell you when new (limited time) free ones are.
I'm a Brainbench Certified Internet Professional (BCIP - Web Designer). To get that title I had to pass 7 other tests... it would have cost $400 to take them all but I did it all in a weekend when they were free.
They expire after a year, and mine expired 07/05... but I don't really care. I had all the framed certifications hanging in my offices when I had my design studio... something for clients to look at while waiting.
Like a doctors office.
you should check it out.