Return on investment is often measured as revenue divided by costs, sometimes expressed as a percentage. For example if a marketing campaign cost £10K but brought in £20K of additional revenue then the ROI is 200%. Now if you are just given the ROI you'll find you are missing any of idea of scale. The same ROI could be achieved with a revenue of £200 and with one of £200 million. So it would be nice to see cost, revenue and ROI visualised all in one go. There are a few ways to do this but after playing around I came up with the following representation which personally I like the best. It's a simple scatterplot of cost against revenue but since all points on straight lines radiating from the origin have the same ROI it's easy to overlay that information. If r is the ROI the the angle of the corresponding spoke is arctan(r).
Note you can drag about the labels. That's my preferred solution for messy scatterplot labelling.