I use the free distribution of Fusion Charts, and have to say it's excellent. Used it with a MySQL backend / PHP frontend to build an application monitoring portal, and been very impressed with what can be achieved.

Will keep an eye on this thread in case any interesting suggestions come up.

 

Google offer a free API for web charting.

http://code.google.com/apis/chart/

But we still use Fusion Charts as nothing compares for the (small) price.

 

Fusion charts looks amazing tbh, wish it wasn't so expensive though, as I'd like to use that in a few sites I've done.

 

We've got the Developer Licence for Fusion Charts and it's absolutely fantastic, it's incredibly simple to use and code with and the level of support/documentation is great too.

Nearly everything you do is easily designable and customisable too.

We've rolled it out on a fair few sites and used it pretty darn extensively in a fair few.

We've also included it into Visual Basic programs, it's a pretty darn flexible platform.

Certainly don't overlook Fusion Charts

 

Going to send a link to Fusion charts to my boss, its snazzy stuff like this that adds that little extra to projects.