Just in time for the User Forum at Uppsala, the Direct User Support group  produced some educational screencasts that answer common questions about the grid. They are available for viewing here on YouTube and at Vimeo.

Alternatively, you can download them directly to your laptop.

A few samples are

[1] Introduction to Grid Computing
[2] Credential management
[3] Job submission
[4] Data management

(An index of such “Use Cases” can be found here.)