Charts/Graphs that change data with drop down window

Hi,

I can't stay away from this place... It is great hanging around genius's!

In short...
Is it possible to create a chart which changes it's data depending on what item is selected from a drop down list?

In long...
I have financial data on each day of the year and would like to be able to select a month and a day using a drop down list, which will then change the data displayed in the chart. I know I can create a sheet with 365 charts have them display on request but then I would have to create 365 charts. Is it possible to let the data change rather than the entire chart?