I stumbled upon this today. It's from the Microsoft UK Developer Tools team.
I've written an addin for IE to allow users to easily raise a complete bug report. When the user indicates that there is a problem on the page, the addin will create a new Team System Work Item and populate it with the following information:
- A screenshot attached to the work item.
- HTML source of the page and any frames and IFrames attached to the work item.
- Any style sheets referenced by the page attached to the work item
- Any script files referenced by the page attached to the work item
- Details about the user's machine and browser (OS version, browser version, screen size, ...)
Hopefully this should include a significant amount of the information you'll need to identify the problem.
They have a project space on GotDotNet, and you can download the add-in here.
Of course, this only helps you if your users are using IE...