I gave a talk at Drupal Camp Chicago 2009 discussing how to connect other applications to your Drupal site by turning it in to a web service. The talk had pretty good attendance, and I thought someone recorded it, but I cannot find that anywhere online. Instead, I’m in the process of converting the talk into an web accessible format which will hopefully serve as an adequate reference. Until this is complete, please jump ahead to the Slides and Example Code, which contain the bulk of the information.