Codeplex.com is a real treat of many custom solutions for SharePoint.

One of such is the features solution (http://www.codeplex.com/features).

The solution offers WSP files that you can deploy to your SharePoint Farm. One such is the ULS Log Viewer solution.

Firstly, the ULS (Unified Logging Service) in SharePoint logs all events that occur across your server and farm deployment. If you have deployed a custom BDC or Web Part and have errors then the most likely place to find why will be in the SharePoint Logs.

This feature solution adds an additional "Utilities" section under your Central Administration Operations tab. Having to browse and analyse the traditional SharePoint log files in Notepad can become painful - especially if the server is well visited or has a few health issues and has a number of solution applications, custom web parts and multiple data connections and even a EPM deployment.

The filtering ability makes makes fault finding easier.

Other awesome features include a Debugger Feature, Content Type Hierarchy (especially if you have a complex taxonomy), Print List feature, FBA (for forms based authentication - great for the IEE for Intanet/Extranet environments - easier than writing your own), Task Alerts, Toolbar Manager (great for allowing end users to show/hide their menu items). Those are just a few.

Depends on the deployment - but I find these are always involved.