Unfortunately there are not any free web-based tools available for this exam that I am aware of, other than the exam preparation guide, which is available at http://www.lotus.com/certification .
For fee-based services, self-test-software do have a practice exam available at:
In addition, I can recommend the LAEC course "LotusScript in Notes for advanced developers" and there is also the IBM RedBook, "Lotus Domino release 5. A Developers handbook", which is also an excellent resource and can be downloaded from:
This was first published in February 2002