Hey Fred,
yes someone has had a look to the test cases in org.hsqldb.test. I think not only.
of course I can help. I waiting for you todo list and then start. Developing the whole day needs sometimes something to relax. Why not writing some docs or new SQL Tests, or even juint tests.
The only think, so of the developers with english as a first language has to have a look on the stuff I'll write ;-).
Merry Christmas and a Happy New Year
Alex