LogSaw based on Eclipse and free. Log4j log file analyzer, simple to use with easy filtering. Supports several flavors of log4j log files: JBoss, Log4j pattern layout, Log4j XML layout, WebSphere.
Works like a charm. After couple of hours googling and trying several recommended free log4j viewers, this one was pleasant surprise. Have tried Chainsaw, BareTail, Insight, LogExpert, logview4j.
It is released weeks ago, and I guess still builds its way up on google.