Log4net/Logging - What have you found to be useful?

Question

I just started using Log4Net and was looking to see what you have found to be useful in your logging experiences.

What types of things have you found to be useful to log

Answer 1

Another really usefull apender is the DBAppender which may log info in a Database, which is obviously incredibly useful so as to query a log.

More info on this in this article.