I've been thinking, testing, and talking about custom select components and comboboxes a lot over the past year, and finally condensed all of it into a two-part series of articles written for 24 Accessibility. It covers both why this whole mess is so difficult and what patterns are out there, including the new ARIA 1.2 pattern in part 1, and then goes into the results of usability testing and concrete implementation recommendations in part 2.
