After having performed two rounds of usage log analysis on the heels of user testing, we at least have a reasonable idea of how well our system is meeting the needs of our users.  It is clear that we have more work to do, both in continuing to tap our user base via observation and user testing, and in continuing to perform usage log analysis.  I know that this kind of work holds interest for other institutions and would be interested to hear your observations, comments and questions about it.