I personally use mTail to check text log files under windows.
Microsoft's Log Parser (http://www.microsoft.com/technet/scriptcenter/tools/logparser/default.mspx) rocks. It works with the Event Log (as well as many other inputs) like you want, provides tons out query options (including T-SQL!), and outputs to just about anything you want.
TechRepublic has a brief overview here: http://articles.techrepublic.com.com/5100-10878_11-5034923.html.
Further, TechNet (http://technet.microsoft.com/en-us/library/bb878032.aspx) demonstrates how to pump data to a SQL DB and generate reports.
Ben, If you like the log4net dashboard, I would just like to mention that the log4net Dashboard has provider architecture for log source providers, this means that you can write your own provider to read whatever log source you have and get it populated into log4net dashboard.
Log4net Dashboard comes with a SDK that contain the documentation of the provider interface as well as the source code for the standard providers (log4net SqlServer, log4net Oracle, log4net xml and an eventlog provider).
The log levels displayed within the Dashboards is decided by the provider all the log4net providers use the log4net levels (ie. Fatal, Error, Debug, Info). But the EvenLog provider uses the standard event log levels (Error, Audit Failure, Warning and Info). An Enterprise lib provider could use the levels used within Enterprise library.
I would like to view my Logs in DB done using Enterprise Lib, all these suggestions or for event log or flat file. Any suggestion for DB, it needs to be free to use and no customization needs to be done.
You can try YouLog4NetViewer, it's open source en Codeplex : http://yourlog4netviewer.codeplex.com/
even I am looking for a good log viewer to view logs on my sql server db (i am using log4net) currently , has the author of the question found a good log viewer for viewing log4net log files stored on a db ?