Here is my policy on allowing people to use my images on blogs & web pages & so on. I'm not against it -- in fact I see it as people helping my artwork gain exposure. Most of the images online are low-res & not much use for anything other than screen resolution work. So, by all means, you can use my images for non-profit stuff, such as your personal blog, providing:
-- You don't alter the image (except for resizing)
-- You give me credit (my name plus the URL of the web site where you found it would be nice)
-- You don't remote link the image -- i.e. you copy the image to your hard drive, then upload it to your web page. I'm not very happy when people simply insert a link to the original file on my own web site, as they're stealing my bandwidth
-- (Optional) you send me an e-mail with the URL of the page where the image resides
I think the above is pretty reasonable & I hope I didn't just shoot myself in the foot, legally speaking...