Here is another background which I will let you download and use for your own nefarious purposes. Getting those edges to line up was a superlative pain in the ass.
After much messing with Pixelmator in trying to make a tiled background, I finally Googled around today and downloaded some Quartz Composer effects. One of those effects was an Offset plugin, which is what allows us to make sure an image tiles seamlessly. In celebration of this acquisition, I will share with you my first new tiled background made in Pixelmator.