The other day on rounds, I saw a patient with an oval pupil. She looked ... feline. I took it as an incidental finding (my mind was really on presenting the next patient, and finding some coffee) but it's possibly quite serious, according to several sources. Damned cool-looking, though: click on "oval pupilla" at this site for a glimpse, or check out this stunning view of the iris in Adie's pupil (which, I must say, is also on my differential).