Thanks for the example Paul. That definitely gives me something to work with.
Ralph, that's a pretty impressive test! I've long been an advocate for pushing the bounds of jpeg compression (i have my default compression at 70% in Photoshop). I've noticed that on most photographs, (especially images of people) I can go much lower than that without introducing noticeable artifacts.
However, on graphics with large blocks of solid color (like web graphics for instance), the compression artifacts become more pronounced. So, this technique is much more suited to photographs than graphics.
Very good information.
Note: If you are using WordPress, you can programatically set the compression level for uploaded images. WordPress defaults to 90% compression level for Jpegs!!!