xThink Calculator is one of the more unique programs seen recently. It's an on-screen calculator, but you don't click on or type in numbers—instead, you draw them just like you did in your notebook in high school, saving yourself the trouble of having to deal with convoluted sets of parentheses and other symbols to write a complex expression. Obviously, this software is intended for tablet PCs, but even using my mouse the program was able to interpret my scribbles pretty consistently.