Vectoraster is a graphics utility for creating vector-based raster patterns and halftones based on bitmap images.
The raster patterns and point shapes can be freely configured to produce many different styles, with the resulting raster shown in real time as you change the parameters. The rasters can then easily be exported as vectors to EPS or PDF files, as images to JPEG, PNG or TIFF, or simply copied and pasted into most graphics software.
You can download and try Vectoraster for free, but with some limitations. To remove these limitations and get the full version you have to pay for the application.