Martijn - The Venn View should do this, assuming you have already defined Named Queries for each data subset you want to plot.

Coloring is based on relative number of records in each subset, as described here:

http://forums.visokio.com/discussion/1758/venn-diagram-colouring-optionss

Hi! All data subsets contain different amount of records, but the venn diagram shows each subset in the same size.

The total overlay area is (currently) is not at all proportionate to subset record count...this is possible to do with only 2 subsets, but becomes much more tricky with 3 or more subsets...

I have classified this as an idea that 2-subset behavior at least have a proportional overlay area option.