Nothing gets Force.com developers more animated than the topic of Apex testing and code coverage (other than maybe Governor Limits!). Anand Narasimhan, a Principal Consultant in our consulting group and general Force.com 'Top Gun', and Ryan Spraetz, Product Manager for Apex, recently presented an excellent webinar on Apex testing best practices. The recording for that webinar is now available here, along with an FAQ and a link to the presentation slide deck.
The webinar featured a short introduction to the Apex testing framework and general testing 101 before jumping into some more advanced testing patterns. The advanced patterns included testing HTTP callouts, testing a Private security model and the use of Test.isRunningTest (bet you didn't know about that one). Anand also covered some testing anti-patterns that are a must-see for any Apex developer. Developers (you know who you are) can sometimes be creative in how they follow the letter of the Apex testing framework while violating it's spirit and so its great to have these anti-patterns recorded and documented.
Now, lets make sure I practice what I preach. Spell check done. Ergo 100% test coverage. Deploy blog to Production.