I've had a casual interest in usability and user experience for a while now, but up until now the interest has been passive: reading widely and observing friends and family use web sites.
Yesterday, however, I was involved in my first user testing session. I've been reading Steve Krug's Rocket Surgery Made Easy, which I highly recommend for getting started with user testing, so I had a reasonable idea what to expect. But I was still shocked at how glaringly obvious important usability issues seemed after less than half an hour with someone who hadn't used the software before.
Wow, the top navigation menu is completely invisible!
Now to work out how to get more user testing happening for open source projects.