Depends on the application you're writing (Score 2, Interesting)

It depends on the app you're writing -- is it a web app, a database app, a userspace program written in C, a Perl/Ruby script, or.. At work we created our own logging library in C to emit log events for different levels, e.g. informational, debugging, warnings, errors, fatal messages. We then have wrappers around that library so that languages like Ruby can access that logging library. But on hindsight I think I would've just used syslog if I had to start over. :)