We just recently created a project on CodePlex that is an Open Source Debugger Extension project called ODbgExt.  This is an extension is going to be created by the community.  So everyone will have a say in what happens with it.  The NTDebugging blog has more information on this but I wanted to copy the goals of the extension.

• A Graphical representation of Kernel, and User mode execution time by process and thread, while correlating to idle / non-idle time
• A Graphical representation of idle time for kernel and user mode.
• A Graphical representation of pool resources used on a per process bases along with handle table counts.
• Hang detection, scanning for various conditions that could cause hangs in a system or user mode process.
• Detailed system information such as oldest and newest binaries.
• Binary info based on vendor name
• A better dissembler that colorizes calls, jumps and indents to show code flow
• Extensive use of DML (Debugger Mark-up Language) to enable more point and click debugging within windbg.
• Support for a SQL Database backend to allow storing information about debugging sessions or binaries in a SQL Database.
• Warnings when critical thresholds are exceeded such as handle counts over 10,000, Low PTE Conditions, etc.
• Simplified searching for pool tags in binaries.
• Support for VBA for Windbg
• Dump annotation, via dump streaming; the ability to embed data into a dump via the debugger extension and later retrieve it. (Imagine embedded debug notes)
• Embedding a snapshot of performance data in the dump at the time the dump is taken, ie. CPU, IO etc

As you can see, these are some great ideas and an extension that has these abilities would be a very valuable tool to have.  Please go check out the project and get involved.