ResponderCon is a conference dedicated to helping cyber responders, and DFIR examiners investigate digital intrusions. While other events focus on preventing the attack, this focuses on what to do after it happens.
The Open Source Digital Forensics Conference focuses on tools and techniques that are open source and (typically) free to use. It is a one-day event with short talks packed with information. There are both tool developers and users in attendance, and this is a unique opportunity to learn about new tools and provide feedback.