For v1 of Peggsite, I was the primary developer for both front end and back end code on PeggSite. On the back end, we use MySQL and PHP. On the front end, we use Backbone.js and Require.js. The idea, and all of the design is done by my co-founder, Kirk Love. The code is all pretty much all mine (Kirk is helping with some HTML/CSS). I designed the database, API, the entire front end, and managed all of the back end AWS infrastructure. This is a very front end heavy application.
For v2, we decided to concentrate all of our efforts on the iPhone app. We scaled the presence of the web site back significantly, and doubled down on mobile. This entailed me quickly getting up to speed with Objective-C, and then spending the bulk of my days in XCode. During this process I learned a ton about all aspects of native iPhone development.