Wow! The popularity of the Sparklines library has been overwheming!
It was mentioned on the official Rails blog and other respectable blogs.
A few modifications of the code have already been posted elsewhere. Kazuhiro Yoshida has posted a version that uses the pureimage library instead of RMagick ( Japanese | English via Babelfish )
Thanks for all the comments and suggestions. A gem and a rails generator are being written as we speak…