DV should have at least rudimentary charing and graphing capabilities built in. JFreeChart seems to be a natural solution for this. Shouldn't be too difficult to implement... if we architecturally treat a graph/chart like a subreport, then the resultset that the "subreport" uses could be fed into JFreeChart, the image generated and saved in memory, then inserted into the output.
This may be a problem with regard to making it work across all LE's... HTML seems fairly obvious... PDF shouldn't be too tough... the others might be more difficult.
The bottom line is that DV can't do charts and graphs now, and adding that capability might be a real nice thing.