Check http://www.tekmetrics.com/

It offers on-line tests/certifications. It's still free for a limited time.

The tests are good, with time limited questions and good coverage of the language/domain. You can use any documentations you want. But, from what I've seen, the questions cannot be answered by simply looking into a help file. I liked especially the fact that questions concentrate more on correct understanding and use of the concepts/language than on specific function parameters/names/etc. Ie: more on the things you cannot find in on-line docs in less than 1 minute. :)

The bad part is that... there is no VFP test. :( But it may be a good training for those wanting to pass other certification exams as well for simply testing your knowledge on different languages/areas.

Vlad