E-xperiments.org is a repository of online psychology studies conducted by Tal Yarkoni, Ph.D. Currently, you can participate in the following studies:
This study investigates the relation between people's personalities and their online writing style. You'll answer a series of questions about your personality and your blog (if you have one). Anyone can participate, whether or not you maintain a blog. You can choose to receive some information about your personality scores at the end. Takes 15 - 30 minutes.