Here is a video that I created that details how to use a program called Alchemy. (CLICK HERE TO VISIT THEIR SITE TO DOWNLOAD) This application is great for quickly generating shapes and ideas. It creates vector art for you so you can take it into other programs like Photoshop and blow the art up to what ever size you wish.
This program is great for quickly generating thumbnails for your projects.
Hope this helps - NickZ. :)