It seems like most of the libraries I use in .NET output log statements via log4net, which is great.  The one thing that often occurs though is information overload, especially when I set my root logger to DEBUG.  Since I follow the logger per class convention, and I name all my loggers based off of type its super easy to allow DEBUG messages for my code, while turning other packages to INFO.

    <root>
      <level value="INFO" />
      <appender-ref ref="ConsoleAppender" />
    </root>
    <logger name="GalleryPlayer">
      <level value="DEBUG"/>
      <appender-ref ref="ConsoleAppender" />
    </logger>

The above lets NHibernate (or whatever else) log at the INFO level, while my code under the GalleryPlayer namespace logs at the DEBUG level.