In my last post I told you about iGoogle, the homepage you can create that displays when you go to Google's homepage. You can add widgets for weather, Facebook, calendars... just about anything. I also told you how you could use Google's built in theme creator to customize the look and feel of your iGoogle page. However, that method - While easy - isn't very powerful, and doesn't allow you very much flexibility. So as an alternative, I give you the, "Developer's Method."
Google allows developers to create custom iGoogle themes that are more advanced than what we can do with the built in theme editor. Using XML, which is basically a form of computer code, developers can write their own themes into an XML document, submit the document to Google and get their custom theme in the theme library. Unfortunately, if you're anything like me, you don't know how to write XML.
Enter igThemer. Located at www.Hawidu.com/themes, this is a free to use tool made by Brad Czerniak. Essentially, it gives you a form that you can fill out, choosing custom colors for everything on your iGoogle page. It even gives you a live preview of what your theme will look like.

The part that you can really have some fun with is the images you can upload for the banner. There are two places for images in igThemer: Center Image URL and Tile Image URL. igThemer can't host the photos for you, but you can upload them to something like Flickr or Picasa, copy the URL of the images, and paste them into the appropriate wells in igThemer. But what is the center image and tile image, you ask?
The center image is what will appear in the center of your banner, directly behind the Google search box. The tile image is an image that repeats across the background of the image. The center image can be almost anything, even transparent if you make it a PNG file. But the background image has to be able to tile, meaning that if you line up several of the images in a row, they just look like one big image. To give you an example, here's the photo that I created for my tile image.

It's a little hard to see, but if you line several of these images up side by side you won't see the seams. The images can be as wide as you want, but if you want them to display properly in your iGoogle theme they must be exactly 175 pixels tall. If you want to check out the theme that I created, you can view it here.
If you have any more questions regarding creating an iGoogle theme, post them in the comments below. I hope you found this helpful, and have fun being artistic!