Usability tests are very simple, and you don't even need lots of people to get useful results, so they are quick, affordable, but still very powerful.
There are many usability tests that can be done, some involving expensive laboratory setups. The big benefits for normal mortals come from fast, cheap, simple tests, so that's what I offer.
A usability test is simply a test to find out how usable your website is. It exercises your text, your design, your navigation, your content. Users arrive, use your site for a purpose, and report on the things they like, and more importantly the problems they encounter or things they don't like. You'll end up with a very actionable to-do list.
Usability isn't a wishy washy term, it's a serious area of study and there's an international standard for it, ISO 9241.
I have a network of usability testers, and I know rather a lot about them. So if you want to know what muslims think of your site, perhaps I can help. Or 12 year olds. Or Mac users, or married people, or vegetarians.
I also ask plenty of general questions about how our testers relate to your market and your type of product before taking them to your site and asking them to work with it. So you get to know about how they relate to your products and market. When you know your market, you can write and design more effectively.
I then take what they tell me, sort it all out so it makes sense and is readable, and report it back to you. It takes a while to administer it, create the questionnaire, collate the results and so on, but otherwise it's straightforward. I can usually deliver your report in about a week.
(I haven't got permission to publish this one yet, so it'll have to be anonymous for now)
Personally, when I first saw this site I appreciated the simplicity of the coding behind it, so forgave it its styling on the basis that at least it's recognisable and that I was going to iteratively improve it.
Users weren't as forgiving. They couldn't find out about delivery, wouldn't download pricing files for security and "it's ridiculous, just publish them on the page" reasons, and couldn't forgive the site for not having a decent shopping system with pictures of the products and good information. Simply, they would never buy from it.
What they did like, however, was the wide range of goods (once that had been pointed out).
Here's one that surprised me. A user preferred a contact form to an email address because it's right there on the page and he didn't have to fire up his email client. On the contrary, I never liked forms because they don't give the email address, and you don't have a history of your request in your email system (so if they don't reply, you don't know what you said nor when). If I'd given an email address only, that would be a great example of me designing for me, and not for the client.
I distilled from that a to-do list of ten items, a list of four key sites the users liked, and a load of information about people's attitude to organic food, how people shop, and home-delivered groceries.