Adam Nathan has posted a VS.NET add-in to gotdotnet.com that lets you easily find and insert PInvoke signatures directly into your code, using the PInvoke.net web site as its data source. Bugger! I had already started writing a similar add-in for my entry to Roy Osherove's add-in contest. Guess I'll have to come up with something else.
Very nice tool (and web site). Installed.
Update - Updated the URL, which changed after my intial post.