The Great Technical Talks — Sandi Metz
I’ve only listed the talks I’ve personally seen and can attest are AMAZING.
Solid Object-Oriented Design — Gotham Ruby Conference 2009
Go Ahead, Make a Mess — Rocky Mountain Ruby 2012
The Magic Tricks of Testing — RailsConf 2013
All the Little Things — RailsConf 2014
Nothing is Something — RailsConf 2015
A larger list of Sandi Metz’s talks, including ones I have yet to enjoy, may be found over on our good friends at Confreaks.tv.