Thanks to the genius of Andrew Kramer from Video Copilot, I now understand how to create a realistic raindrops-on-glass effect using nothing but After Effects (no video footage or plug-ins required). Thanks, Andrew! The look (and mood) are enhanced by a Camera Lens Blur filter-generated rack focus from the drippy panes to photos of the city beyond. Cool jazz performed by JCNY adds mellow ambience to the rainy scenes.
Here are links to the resources mentioned:
Art List music / Art List song: Night Time, Central Park