I have a Livescribe Echo Smartpen and love it and find it to be very useful. The Livescribe smartpens are pretty cool. They record what you write, and hear, and then you can load this into your computer to keep a digital copy of your written notes and even share your notes with others.
(full review here)
The ability to record your hand written notes is very useful in Math and Science, since it’s very hard to take notes in these areas with a keyboard or even a tablet/pad. It can also make an audio record of what you say or hear as you are writing and it timestamps and syncs the written notes with the audio notes.
The model I have is an 8GB pen. You get the desktop software, stylus tip, two ink cartridges, the cable, a starter notebook, and 500MB of personal online storage. The 8GB Echo retails for $199 so it’s not cheap, but it is another tool that can be very useful in education, business, and even just for taking personal notes. The 2GB pen is only $99. There are discount prices available to educators, anyone interested can email firstname.lastname@example.org for details.
UPDATED PRICING : You can get 15% off the price of a Livescribe Pen by using this link (directly to Livescribe, not secondary vendor) They are also offering a free year subscription to Evernote Premium.
The main reason that I see these as an essential tool for many people is the ability to record hand written notes. Many people, myself included, take notes very efficiently with pen and paper, using symbols, diagrams, arrows, and the like to make the notes more meaningful. It’s also great for people who have to take notes using math and science equations and symbols. Being able to easy capture, save and then share those notes is a great thing.