Update 10/4/10: I fixed an issue where the dots were being cut off by the edge of the canvas. Next up, figuring out the correct aspect ratio using the 45 degree rule.
Update 11/17/10: Took out the pre-canned sparklines and added a textarea so you can make your own. In the code I'm trying to set the scale, too, but it's currently disabled.
Update 11/21/10: Now setting the y-scale to the min and max of the data (previously it was always setting the min at zero).