25 great free resources for making charts - FrancescoMugnai.com. Here you have a new roundup about a bunch of great tools for making charts and graphs.
You can choose between web generators, flash, javascript libraries, Silverlight or PHP classes. At the end of the post you find also 3 tutorials to make pure css bar graphs and another one for Adobe Illustrator. JS Charts (JavaScript based chart generator) Google Charts API: an ASP.NET 2.0 Server Control. Today, I just saw that Google released their Chart API.
Basically, the Google Chart API allows you to dynamically generate charts for use in your web applications. All you do is pass your data in the querystring and an image is returned. This isn't really a service to get too excited about, but it is pretty simple to use. And, it's Free. I decided to code up a small ASP.NET Server Control that uses the Google Chart API to put simple line graph charts on a page.