Mobile before the iPhone
This was a different time: mobile web development before the iPhone. Android phones looked like Blackberries and Blackberries were still popular. Telecoms decided where the home page of phone browsers went (and it was usually their mobile portal, because no one else made mobile websites). People paid 15c per news story and mobile ringtones were a bigger market than record sales. Performance and markup was important because otherwise things simply didn't work. The support of dropdown elements in mobile browsers was an exciting step forward. I used Microsoft Visio for wireframing. Flash was still a thing.
I learnt about a lot at 3, things like wireframing, use cases, user testing, card sorting, and paper prototyping. My boss told me to read The Design of Everyday Things on my first day. Over my two years I worked on a range of features from billing and usage to Mobile TV to Playboy. The most important thing I learned though, was that some of the biggest and successful companies in the world (3 included) can be brought undone by a great experience they didn't think of. Pretty much everything I worked on there was gone within a year of me leaving, because Apple and the iPhone changed the world we worked in. And because most of our work didn't survive in that new world.