The idea is great as people will always like to see a personal photo on their homepage. As usually, iGoogle managed to make another mistake: the theme creator page has been down until today.
Now that it's finally available, you can see the tool is very basic and it only lets you upload an image, choose a header text color and a theme color. It's very difficult to crop a photo so that a certain region is visible, the color palette doesn't include too many options, you can't find the themes you've created to apply them to other pages and you need to accept a license agreement after creating a new theme.
If you need more control, try the two advanced editor previously mentioned or create your own XML files using iGoogle's API.
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