Google Chart Tools is also quite nice: https://developers.google.com/chart/

Actually, this is a perfect time to ask: I've been trying to find the best FOSS charting tool for a (for-profit) RoR app I'm building. Google-visualr seems to be the easiest to use: https://github.com/winston/google_visualr

I made a list of other possibilities here: http://bernardomenez.es/graphing-on-rails

Any tips on a good gem/framework to use for an RoR newbie would be much appreciated...

There is morris.js: http://www.oesmith.co.uk/morris.js/ It has been featured in a railscast: http://railscasts.com/episodes/223-charts-graphs-revised

Not really a tip from the RoR side of things, but I do have experience with the Google Chart Tools.

Its a decent library, but keep in mind that Google is in control of the source code. I'd personally look for something that uses a library you can host yourself.

More items for your list.

- D3js http://d3js.org/

- NVD3 http://nvd3.org/

http://dygraphs.com/ is nice too

This is the only graphing library that seems to believe that the challenge is "display lots and lots of data quickly in a legible fashion" as opposed to "take small amounts of data and render it in a way the user will consider pretty". I love dygraphs ;P.

I'm using jqplot: http://www.jqplot.com/

If you are using PHP, check out http://phpchart.net. It's based on jqplot.

I use Dojo's charts. http://dojotoolkit.org/features/graphics-and-charting