Ink Desktop
From the site -
If you have a Tablet PC, you’ll love using Ink Desktop. It’s like having a portable dry-erase board on your screen all of the time. Whenever you want, you can jot down a phone number, directions, or top priorities for the day. And, for added fun and functionality, don’t forget to download Microsoft Experience Pack for Windows Vista, which contains four programs that provide unique functionality and fun to enhance your experience using a Tablet PC. It’s available separately for download.
This seems like it would be incredibly valuable for both students and teachers using Tablets!