We have long had the ability to digitally sign documents on the computer for a while now. However, in the past, they have either involved the use of some elaborate geek skills or a paid third party application to accomplish signing a document without having to print it, sign it, and then rescan it back into the computer.
Now it is a very simple, and free, process for those of us running Lion on a Mac. The free Preview application that ships with all Macs now has a way to create and save digital signatures.
The folks at TUAW (The Unofficial Apple Weblog) have a quick tutorial explaining the steps involved. And if you are a visual learner, below is one of the many youtube video tutorials I found showing how to digitally sign a document with preview.