The University of Arizona's UACBT service (Computer-Based Training) offers 24/7 availability of FREE online training to over 1000+ courses and 98,000+ video tutorials, covering a broad range of topics and applications.
Most tutorials have between five and fifteen hours of content. Each tutorial is divided into lessons from 2-10 minutes long on average. Each lesson is available as a Flash, QuickTime, Adobe Air, or Adobe Air for Linux movie. You can stop, start, rewind, and review each lesson as often as desired.
You can get more information about the UACBT service on UITS' website.