Many of you probably know that you can specify your own diff/merge tool. One thing that's not mentioned on that documentation page is that you can specify * for the Extension field to change the default diff or merge tool.
James Manning recently put together a nice post on configuring different diff and merge tools, making it easier to properly configure the tool of your choice. This is most useful for merge, where for v1 a number of other available tools offer a better experience than diffmerge.exe in the more complex cases.
One of the extensibility points we have in Team Foundation V1 is that you can configure any other diff and merge tools you want. The purpose of this article is to start collecting the most common ones we know or heard about in a central place so people don't have to figure these out on their own.