Vectoraster is a Mac OS X graphics utility for creating vector-based raster patterns and halftones based on bitmap images, an effect that has been popular in illustration and design the last couple of years, but is quite tricky to achieve without the proper tools.
The raster patterns and point shapes can be freely configured to produce many different styles. The resulting rasters can then either be exported as vectors to EPS or PDF files, as images to JPEG, PNG or TIFF, or simply copied into most graphics software.
VectorRaster is $29 ($12 upgrade from previous versions) and a demo is available for download.