Usability Tests of Widely-Used Software

Question

Does anyone know where I can go to find the results of usability testing of widely used software?

I want to be able to make informed decisions about:

• which bits of existing packages to copy in my software
• how to choose between multiple packages (programs, components, etc).

Really, I would be grateful for anything here.
I'm interested in: websites, office software, email clients, you name it.
I want objective, empirical information about what's good and what's not in specific instances.

This question is inspired by my answer to this question about markdown.

Answer 1

For starters you can try the Interface Hall of Shame, just as well as the one of Fame.

Answer 2

useit.com gives out awards for 10 Best X on a semiregular basis, e.g., 10 Best Intranets of 2009, 10 Best Application UIs of 2008, etc.

In case I didn't make it clear, useit.com is the web site for Jakob Nielsen, and the Top 10 lists are the results of usability studies the NN/g conducts.