Well I m going to cover the topic how to generate charts using rails. there are number of options available such as follows
Here are the plugins through which we can generate charts in rails
1) Gruff charts http://nubyonrails.com/articles/gruff-graphing-library-for-ruby
2) Sparklines http://nubyonrails.com/articles/sparklines-graph-library-for-ruby
3) Scruffy charts http://scruffy.rubyforge.org/
4) Ziya plugin http://liquidrail.com/2007/1/4/charting-the-rails/ (flash charts)
I found google charts the best of these..( ofcourse [...]