You know the Tile Game widget, with the picture of the tiger? I got tired of the tiger picture, so I attempted to change it to another picture. Turns out it was pretty easy.
[robg aside: Temporarily changing the Tile Game's image is quite simple -- make sure the Tile Game widget is open, then start dragging an image in the Finder, activate Dashboard, and drop it on the Tile Game widget. Your image will replace the tiger, at least until the next time you close the widget. This hint explains how to permanently change the image on the widget.]
First, create (if you don't have one already) a folder named Widgets in your user's Library folder. Now navigate to the top-level /Library » Widgets folder, and copy the Tile Game file to your user's Library » Widgets folder. OS X will first look for widgets in your user's folder, so we'll modify the copy of the widget, not the original.
Control-click on the Tile Game file in your user's Library » Widgets folder. (Make sure you're in your user's Widgets folder, not the top-level Library » Widgets folder.) Select Show Package Contents from the pop-up menu, and navigate into the Images folder. You'll find the familiar tiger image in the file game.png. Rename this file to game_old.png.
Now, to choose a replacement image. I looked through my iPhoto pictures and found an image I liked -- a turtle I saw on the beach in Hawaii. In iPhoto, I cropped the image with a square constraint. Then I exported the image as a PNG to my desktop using the "small" setting. I think small is sufficient -- if the image is 200x200 pix that's probably fine (the actual size of the game.png image is 144x144). Of course, I named the file game.png.
Lastly, I copied the new game.png to the Images folder. All done! When relaunching the widget, my new turtle image is the puzzle's image.
You can take it a step further if you want. You'll notice that when you load the Tile Game, it displays a placeholder image while the widget loads. This placeholder image is the file default.png in the top level of the Tile Game bundle. It's a combination of the game image (game.png) and the white border (default_white.png). Using Photoshop, it's pretty easy to overlay the turtle image on the white border to get a new default.png file. Just be sure to save the file as a 24-bit png, so the shading around the edges looks correct. Again, the exact resolution doesn't seem to matter, but 200x200 seems to work well.
When I replaced the old default.png file with the new one, I had a seamless turtle-based tile game experience. It's not an earth-shattering change, but I thought it was kind of neat.
[robg adds: With a bit of scripting work, I could foresee a clickable-app that would change the tile game widget to some random image chosen from a specified folder. Such fun is left as an exercise to those with more scripting skills than I, however.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=2007091805323389