SKForum is an open source (see
licensing) web-based J2EE forum application. But it's so much more, it's a comic system, an addressbook, a wiki, a timetracking system, a todo list, a poll system, a guestbook system and a few other small nuts and bolts.
SKForum was first taken into use in september of 2000. By july of 2001 it had grown to 6 464 lines of code, and at october 2003 it is at 49 067 lines total. Of these 37 596 are java source file lines.
See Other Best Forum Systems Projects in Java: