I've been going over the "sim.util.distribution" implementations and I've noticed that the code comments (JavaDoc) has several inconsistencies. I know that the online docs don't include these comments (yet?),  but if you DO generate the docs someone should review the descriptions of parameter boundaries.
For example, in ChiSquare class documentation (line 19) the following is found:
 * Valid parameter ranges: <tt>freedom &gt; 0</tt>.
In fact, the parameter must be greater than or equal to 1.0 or an ArgumentException will be thrown in "setState(double freedom)" (line 142).
Other inconsistencies exist elsewhere, but I'm just pointing this one out so you can be aware that a thorough review should be conducted if you plan on publishing the class docs for these distributions. Otherwise, you could end up with quite a flurry of newsgroup queries, or worse, a lot of broken code. ;-) 
Ben S.