ACID is a PHP-based analysis engine to search and process a database of 
security incidents generated by the NDIS Snort.  The features currently
include:

 - Search interface for finding alerts matching practically any criteria.
   This includes arrival time, signature time, source/dest address/port,
   flags, payload, etc.  Furthermore, these queries can be made arbitrarily
   complex to satsify almost any parameters.

 - Statistics:
     - % of traffic for each protocol
     - Alerts: # of src/dst IP, last/first arrival time
     - Graph # of arrived alert over a period of time
     - last x-number of alerts by protocol

 - All features are provided in real-time 

WWW: http://www.cert.org/kb/acid/