Thanks everyone! Elizabeth, here's how to get awesome pics to use on your blog for free:
1) Go to
http://www.flickr.com/search/advanced. This is Flickr's advanced search page.
2) Type in your search term.
3) Scroll down and check the checkbox for "Only search within Creative Commons-licensed content." This is important, because you only want to see pics that you can legally use for free.
4) Hit Search...
5) Where it gives you three Sort options at the top, click on Interesting. This is the other really important part.
And there you go--you should now see the cream of the crop laid out before your eyes. If you have a user account you can sign in, but you don't have to have an account. (I like to so I can "favorite" pics to use for later.) I'm sure most people have used Flickr before, but the key is to search Interesting within Creative Commons; otherwise, it's time-consuming to separate the wheat from the chaff. (I just used two cliches in a single paragraph!)
Here's the page that explains what you are allowed to do with Creative Commons pics and how to give attribution:
http://www.flickr.com/creativecommons/
Hope this helps!