Yahoo! Mail is Open for Development — you can write apps that sit in Yahoo! Mail, using and extending the UI as well as taking advantage of APIs that access and alter the email.
10TB of US PTO Data (Google Books) — the PTO has entered into a two year deal with Google to distribute patent and trademark data for free. At the moment it’s 10TB of images and full text of grants, applications, classifications, and more, but it will grow over time: in the future we will be making more data available including file histories and related data. (via Google Public Policy blog post)