This site has information on every aspect of making a presentation, including working with visual aids, presenting data in a meaningful way, and dealing with the inevitable presentation anxiety.
Lots of practical information on this site, specifically geared to students making job interview presentations, but interesting and useful for any presentations.
This is an article from the Harvard Business Review, written by Chris Anderson, from Ted Talks. Very interesting with several videos from Ted Talks to illustrate points made in the article.