Thanks for this list... but I actually found this thread because I was looking for a utility/application that specifically allowed you to combine multiple controller inputs into a single virtual controller.
You are probably thinking of PPJoy.
It was updated somewhat recently to support 64-bit and newest Win systems, but still requires special steps to work.
And yes, it's still a bit buggy and difficult to set up. Not much changed except the new OS support. And, unfortunately, the developer has shelved the project, claiming he will no longer continue development on it. He said he would release the code if anyone wants to continue where he left off, but doesn't look like anyone has or will at this time.
You can see about it here: http://ppjoy.blogspot.com/