A few examples of how companies actually lost my custom because of bad usability (obviously, inspired by Robin Grant's post today)
First I've tried to register my new Sony TV - it was an opportunity to get 1 year free accidental damage cover. I had to activate the CD-ROM, but it didn't work: everything after the first screen was frozen. So, I threw it in the bin, together with Sony's opportunity to get some really valuable personal data from me.
Second, I've tried to register for Nationwide's online banking service. It took me 5 attempts, because several security data fields had a set format that had to be followed, but that was not explained. The error message didn't help either. Finally, instead of instant access to my account data, I will be contacted in 3 days with additional security information for accessing the account.
Finally, I've booked Insure&Go travel insurance tonight and although the quotation was for £99 I was eventually charged £100 without an explanation. None of the fields in the form were marked as mandatory, despite only one of them not being such. Finally, when I've tried to download the PDF version of my policy, I'd got the error page.
It is mind-boggling that things like these still persist in this day and time. Idiocy still seems cheap, as there is so much of it around.