Vectors lend themselves to generative creativity more than any other visual computer element. Not only are there completely generative vector applications but even well known desktop software such as Macromedia Freehand MX and Adobe Illustrator are to be recconed with in this context.

Auto Illustrator:
http://www.auto-illustrator.com/
Created by Adrian Ward this is an application that will design your work for you starting from scratch, in a completely random fashion, requiring truly minimal input from the user. "Bugs" are planted on the page, they move about as they wish until you choose to exterminate them. Similarly you can add text and arrows. You then apply various filters or let the software connect paths to achieve truly amazing visual material of great sophistication and detail. This software is a must for every serious and innovative designer and

artist to download and experiment with.

Extrusion tools:
Macromedia Freehand MX and Swift 3D posess extrusion tools that can give you truly complex shapes, in bizarre dimensions. Both of them work in a completely generative manner: With FH you simply paste in a path into the static extrsion field on the inspector and your extruded object deforms and transform in the most unexpected way. With Swift 3D you draw random paths into the extrusion editor to obtain generative 3 Dimensional shapes. Both should be experimented with for new, refreshing visual elements.

Adobe Illustrator:
Has a series of filters that will create generative 2D vectors. Especially impressive is the Panopticum Array filter, as well as the Andrew's Filter series.