I need something that doesn't add tables or triggers to the database being audited.  I prefer something that doesn't use trace procedures due to performance, but would consider it.  The main area of concern is auditing users connecting to databases with 'outside' applications like Access, Excel, Query Analyzer, etc. and removing certain ODBC sources is out of the question.  I also need to monitor at least 10 of the SQL servers so price is also a consideration.  I am currently looking at Apex SQL Log which uses live transaction logs or T-log backups, but of course the database has to be in full recovery mode--and I'm not through testing yet.  Any suggestions are welcomed 🙂