Step away from the green, orange, and yellow slide you're working on RIGHT NOW and get over to Colour Lovers, where you can find colour palettes that work.
Use this site to capture a screen shot and then edit it (i.e. draw as many handlebar mustaches and devil horns on people as you want! ...or use it more productively)
This presentation won 1st place in the 2010 World's Best Presentation competition presented by 3M. If you're looking for some good design inspiration, this is it.
"This blog is about creating effective presentations and presentation design. Contents include strategy, delivery, design, techniques, tips and storytelling."