Most of my professional work has been on products that aren't easy to show on the web. Here's what I can show.
Source is currently my main project. It is a hydrological modelling tool written in C#, with Winforms and WPF components. It's a massive peice of software that has been worked on by software engineers and hydrologists for over 10 years. I can't take much credit for it, but I'm touching (and hopefully helping improve!) more and more of it.
Continua CI is a continous integration server, built with C#, WCF, ASP.NET MVC and nHibernate. Paul and I were the primary developers for 2 years, taking it from conception to beta release.
Crashdown is a web publishing engine written with node.js. It runs this site, and most of my other sites. It's the first real thing I that I built with node.
Speedy is a speed reading app, written with Cordova and Angular.js.
todotxt.net is a WPF GUI for the popular todo.txt task list format. It's by far my most popular open source app, with about 600 downloads/mth and 14 contributors. It was my first WPF project, before I had any idea about MVVM, so the code's not the cleanest. It works pretty well though.