I'm a regular core contributor and the author of several popular contributed modules, including Webform and a suite of modules around image and file handling. In September 2013, I forked Drupal in a project called Backdrop, which provides a largely backwards-compatible alternative to Drupal 8.
Some projects I've worked on in the past:
- Drupal 8: Core CKEditor module and Dialog framework
- Drupal 7: File and Image modules author
- Drupal 6: Table drag and AHAH framework author
- A number of contributed modules: Webform, Fivestar, Flag, Form Builder, Link, Insert, and many others
I also co-authored an O'Reilly book, Using Drupal, and you can find many videos of me in the video tutorials at Drupalize.me.