Okay, this is another one of those tutorials that is so easy, I almost feel guilty.
It was inspired by Nanson's Place. I couldn't remember the exact settings for the yellow globe,and found this effect by accident. If you haven't checked out this page,you should. It's AMAZING. Fantastic tutorials, and images that make you just go "I didn't know you could DO that!"

You will need Paint Shop Pro 6 or up, and Simple filters for this tutorial.

Start by opening a new image 150x150 pixels

Set your foreground color to gradient black-white, linear, 0 angle, no repeats. Invert unchecked.
Fill the image.

Image/Effects/Texture Effects, blinds set at 25, opacity 100, color black, horizontal checked, and light from left/top checked.

Layers/Duplicate

Image/Rotate 90 degrees, left checked, all layers unchecked

In your layer palette, switch this layers blend mode to lighten,then merge visible.

This is your base tile. Then you can apply Simple filters for a bunch of other looks.

(fourway average, pizzaslice mirror,pizzaslice mirror and blintz,zoom out and flip)
Use colors/colorise to color. lighten it by sliding the opacity down and then merging all layers.