I am currently running a windows service that creates multiple instances of a class.
At the top of the service class and every other class in my solution, I have som
Use the ADO.Net appender and log to a SQL Server database and just query for the information you need.
Another alternative is the log4net Dashboard: http://www.l4ndash.com/. It does a pretty decent job of integrating logs from various sources, and then slicing and dicing them in different ways. Reasonbly priced, too.