VectorMagic is an online experiment of Stanford University's Artificial Intelligence lab, taking bitmaps you upload and converting them to vector graphic files while-u-wait. Vectorization really excels at simple logos and line art, but this bad boy will take anything you throw at it and deliver interesting results. It has a clean and simple interface, with a Wizard that walks you through the process and then back again if the results make you go "meh".http://vectormagic.stanford.edu/
They even include a brief tutorial for those new to vectorization, or why it's a Good Thing for certain applications. Oh, and while the site has "Login" and "Signup" links in the upper right, rest assured you can vectorize all you want without registration.
I've included some before/after samples by way of demonstration. Each took less than 4 minutes to process from beginning to end. The first is an Audrey Maximus pencil sketch of the Mona Lisa:
Not bad. Kind of screams "Impressionist", but it's a nice effect. It's not a 100% perfect conversion, but I intentionally chose something that would be a challenge, and it worked out well.
Next up, the president of the RIAA:
Whoa! It handles photographs well, don't you think? There's obvious problems with the reflection on his shoulder, but other than that most people wouldn't notice. Note that while these samples are bitmaps (I converted them back again for posting) you can download your vector masterpiece in EPS format.
Vectors! They're not just for making geometry students cry any more.