This page contains a nice collection of Adobe Photoshop CS5 Brushes, which you can easily install into your installed version (CS5 or higher). The brushes you find below are extremely useful for creating abstract effects which you can use in posters, banners, header or background (or any other format you can imagine).
What are Photoshop Brushes?
A Brush is a preset like Actions, Patterns, Gradients which can have any possible shape. Significant is, that the brush has no colors. It will be saved in greyscale and the brush will be in the color you have choosen previously (as foreground color). You can extend your Photoshop experience with various and endless presets. The brushtool is in the Photoshop sidebar (or press Shift + B).
How to use Photoshop Brushes?
Once you installed the brushset of your choice ,you can scale the size in the top menu. Then create a new layer, set your foreground color to (for example) black and just click into the new layer. By clicking the tiny arrow next to the preview image, you see a lot of different settings. These settings let you modify the current brush. You can adjust the opacity, distance, rotation and mayn other stuff.
Here you can download some really cool Adobe Photoshop Brushes for CS5 and other versions.
An extended and free ”How to install Photoshop Brushes” tutorial is here available.