Chart for lower order activities
In the lower right corner, next to the lower order activities it might be nice to have a chart for displaying the relations of these to the currently displayed activity.
Chart for income
I suggest to create the same chart for income too.
What i don't think fits in the current logic.
chart for monthly balance
For some people pie charts really seem to have less informative quality than bar charts, so it might be clever to support the possibility to switch between this two display modes.