Quora is a very popular new service from the ex-CTO of Facebook.  Here’s an image of part of the main page:

Quora usability failure

The top bar shows an entry box followed by what looks like a button with the text “Add Question”. One assumes the two are related because there’s they’re in the same black box, so the expected behavior is that you would enter a question in that top box and click the “Add Question” button.

Initially, when you first come to this site, you browse a bit, then think about a question you might be interested in and want to search, and spend a bunch of time looking for the search box, then throw up your hands and say “How can this site not have search???” It does – the “Add Question” is completely unrelated to the text field.  The text field is the search box, and has not button associated with it because it’s Ajax-driven and shows possible search topics as you type it.

This is a hugely popular site. Draw your own conclusions.