Sharepoint - List of tools for reading ULS logs

Realtime? ULSViewer wins hands down: http://www.harbar.net/archive/2010/10/06/ulsviewer-ndash-the-tool-that-no-sharepoint-practitioner-should-be.aspx

Update: ULS has been resumed officially with updates (Aug 2014) https://blogs.technet.microsoft.com/wbaer/2014/08/22/uls-viewing-like-a-boss-uls-viewer-is-now-available/

If you are looking to dive deep and investigate all facets of the issue, including the ULS, IIS, event logs and even performance logs, you might want to look into the SharePoint Diagnostics (SPDiag) tool that is part of SharePoint Administration Toolkit, a free tool from Microsoft.

This compiles all of the logs from all servers across the farm lets you get a bird's eye view of what was going on at the given time.

It does take a few steps to set up but really can help troubleshoot an issue.

Documentation can be found on TechNet.

UlsViewer is a no brainer, you got to have it. But for debugging realtime on several web front end servers I still prefer SPTraceView by Hristo Pavlov.

This unique tool lets you watch ULS errors as they occur from multiple WFE. You install it on all WFE and one is chosen as receiver. This way you can monitor behaviour even though you don't know what WFE your users are having errors with.

It only supports MOSS currently.