Use images.google.com to grab random images to spice up the blog. Okay, I'm probably overusing them lately, but it's still cool. Now if there was an easy-EASY way to make the white background transparent, I'd love that. You can do it, but it involves saving the image and manipulating with an image editing program. I just go to images.google.com and type in what I want and then right-click (or control-click on a Mac) and "Copy Image Location" and then paste it in the "Add Image" icon in your blog editor. Pick the image location and size and Upload. You can even resize more once it dumps the image in your editor by clicking on it and then dragging a corner around. Very quick and easy. Sure, it could be considered a copyright problem for some images, but for random icon type things, I don't see anyone caring.
UPDATE: Don't just "Copy Image Location" above. "Save Image As..." instead and save it locally. Then upload that using the "Browse" button in the picture upload. It's annoying to explain why, so just trust me on this. :-)