Cassandra Summit 2012 - Slides and Videos
datastax.comSubmitter here. For those who are short on time, these are a few of my favorites:
1. For those unfamiliar with Cassandra, Patrick McFadin's talk (Building a Cassandra Based Application from Scratch) can give you a good feel for how Cassandra tends to be used
2. Greg Ulrich's talk (Servers Fail, Who Cares?) covers some great ways that Netflix uses Cassandra for high availability
3. Scaling MongoDB with Cassandra is a fun lightning talk
Aaron Morton's Cassandra Query Performance talk was great too.