Lumberjack is an on-device logging tool. It turns up the log level, and allows you to view and follow the logs for specific applications from the /var/log/messages file.
For a complete change log, up-to-date instructions, and all other information pertaining to Lumberjack, Please visit the webos-internals wiki page for it: Application:Lumberjack - WebOS Internals. Feel free to contribute to the wiki page as well.
It can be found in the webos-internals feeds, and installed with preware, quick install, palm-install, etc.
Lumberjack is licensed under the GPLv2.