To create simple, professional looking spikes, you must first open up a new document, any size (I used 500X500), and pick two colours as your foreground and background colour.
Go to filter>>render>>clouds.
Now, go to filter>>stylize>>extrude and use these settings:
Type: Pyramids
Size: 30 pixels
Depth: 50 pixels
Random
Click OK and you're done! You can change the size and depth to your preference. Here is a scaled down version of the result:
More Tutorials: 
