I am a co-organizer of the Waterloo Region Drupal User's Group, and I usually present there at least once a year.

I have contributed a couple of contrib themes:

Starlight is a designed, ready-to-use theme. It's meant to be an easy starting point for a customised design. It's a good way to get something that looks presentable early on in a project. It's more content-focused and Drupal-specific than other frameworks.

Starbase is a simple base theme (currently in sandbox). It provides templates with very simple classes (less verbose than Classy), and a starter subtheme with many of the base elements I like to use in a new project (e.g. basic text element formatting, classes for buttons etc.)

Waterloo is an older contrib theme, similar to Starlight but designed as mroe of an out of the box theme.

I have presented at the Drupal North regional summit in Toronto, ON in 2015 and 2018.

I also contribute in other ways, like by reviewing patches, adding documentation, and submitting the occasional patch.