This is the homepage for reflectajdoc, which is a compiler extension to the documentation tool ajdoc from the AspectJ Project. Rather than requiring the source code, like other Java documentation tools from purple-clad companies, this one allows classfiles to be documented via reflection. What you miss is the comments, but who really reads those anyway -- any decently-written API should be comprehensible from the method and attribute names.
Go to the SourceForge Project Site. There are source, documentation, and binary releases.
The build in run using Ant and requires the JDK version 1.3 and AspectJ tools. . . so here are the instructions: