Free PowerPoint templates (must be downloaded as one big file)

Indezine

Free templates and tips for PowerPoints

Online tutorials for basic and advanced PowerPoint plus links to numerous sites and PowerPoints you can download

Free PowerPoint templates for Office on Macintosh

Maniactive

Free templates for PowerPoint and Publisher, along with free graphics of all types

Pointers and articles on creating and presenting PowerPoints

Most templates on this site are available at a cost, but they do have some very nice free templates.

Free templates, sounds, and tips for PowerPoint

Presenters University

Some free PowerPoint templates for PCs and Macs

Free templates for students and educators