This tutorial will teach you how to get a background like this:
This is how you do it:
1. Start a new image with a transparent background. I took the size as 468x60.
2. Hit 'D' to set the colors back to default.
3. Go to Filter > Render > Clouds.
4. Filter > Render > Difference Clouds.
5. Hit Ctrl+I to invert the image.
6. Hit Ctrl+B and mess around with color balance.
7. Click Filter > Blur > Radial Blur.
8. Make the type zoom and amount 100. Click OK.
9. Add text.
This is my first tutorial, so please don't be too hard on me.
Here's a sig made using this background.