I found a great utility from Microsoft named Log Parser. It is a command-line program that will read log files from many different sources and execute SQL style queries against the log entries. From the Overview:
Quickly search for data and patterns in files of various formats, including IIS log files, Windows Event Log files, generic comma separated value (CSV) files, W3C files, and text files.
Create formatted reports and XML files containing data retrieved from different sources.
Export data to SQL tables. You can export entire files or filter the data to obtain only relevant entries.
Convert data from one log file format to another.
Very recommended.
UPDATE (Jan. 20, 2005): An updated version is now available.