Signify is a neat little Perl program that allows a random signature to be generated from a set of rules. You can create multiple sections where each section can be one of an unlimited number of possibilities, each with its own weighting so those really cool quotes can appear more often than others. Sections can be placed next to each other vertically to create columns. You can even format each section independently as left/right/center and top/bottom/vcenter.
Signify is free software hosted by SourceForge and is available in source form here or as a Debian package here. You can contribute to the project here.
Signify requires Perl-5 to run but is otherwise machine independent. (While it might be possible to run Signify with Perl-4, we have not verified such.)