Uses of flash chart is getting popularity day by day. Many medium to big web applications may use flash chart. But small application may ignore it due to complexities of implemention of flash chart. Even some web developers may not familiar with flash to make flash chart.
To make it easy, there are several open source and free of cost flash charting scripts that can be imported in your application. One of them is the Open Flash Chart. So far I have seen, it is the best flash charting script which is very easy to implement. Moreover it supports many languages like PHP (4 & 5), .NET, Java, Perl, Python etc. It provides the library files and examples which will understand very easily.
So test it now, and import it in your next project and impress your client.