There's a creative commons flavor (actually several) that allows reuse for commercial purposes. I'm not sure whether you're searching Google or Flickr or what, but look for options that say something like "licensed for commercial reuse" -- the actual CC license will be one that does NOT say "NC" for non-commercial (so, CC-BY rather than CC-BY-NC).

Elsewise, try istockphoto -- it's a bit of a giant image dump, but they have decent search tools and some cheapish options if you just need a few images on occasion.

(You can also always ask people to use their photos if there's something you really love -- some people won't be interested, others will be flattered, but don't just gank without permission)

massive CC and just-ask x-post!

You can offer them some beads if it works out.

You can also try MorgueFile for photos -- they can be used commercially.

You can offer them some beads if it works out.

And they won't even have to show their tits! Unless you want them to.

smaonster, thank you so much for asking this question and thanks everyone for the hugely helpful answers.

My blogs thank you!

Rock on, y'all. I found one available for commercial use and credited the source on the slides.

Perhaps I should learn to write like this to promote myself:

Duncan’s unique perspective is informed by 12 years of igniting the junction where marketing strategy meets commercial activation within both industrial and consumer categories.

This is from a new energy technology company's site.

Duncan’s unique perspective is informed by 12 years of igniting the junction where marketing strategy meets commercial activation within both industrial and consumer categories.

Huh?

commercial activation?

I need a vocabulary lesson, it seems.

Translation: he's a hot-shot! hire us!