A look at android Intents. Intents are a method of switching between activities. This demo and the accompanying code show basic use of Intents and how to describe them in the AndroidManifest.xml
This is the concept video for droidcast which was submitted to the first Android Development Challenge.
A look at the android Activity lifecycle. Also get to see use of logcat and of gsm via telnet. Java wise this demonstration shows how to implement Activity call back functions.