I'd like to present my newest software as a working beta: Tablelizer. http://pb.quadworks.de/Tablelizer.zip
I am still working on it. Currently, I it works quit good, but there are some quirks left.
I appreciate every feedback possible

Description
Tablelizer opens Diagram-Pictures in PNG or JPG. You set the width, height and reference for this. E.g. the included images data area is about 400 pixels high, but the maximum value is 70. So you set the correct data, and add points. Start with ALT-S, after finished setting the image up, you can add Points using ALT-P. Add another column using the menu, context-menu or ALT-A.
Planned features
- finish the export and clipboard-function (testexport.csv demoes the export)
- display the fetched datapoints using lines
- create a new Digram using the acquired points
- add more languages (currently English, German)
- video-tutorial
- short documentation
Tablelizer will go on sale soon after it hits 1.0.0 for Mac OS X only... I am thinking about a prize tag of 5 to 10 Euros.