This is a pretty modest niche: extracting data from graphs and figures, but GraphClick does what it does wonderfully.

You can quickly define the scale of the graph (in several different ways), then tracing graphs is flexibly and quickly done by adding points (or even automatically tracing both solid and, remarkably well, broken symbol lines).

You can export the data to a spreadsheet, and the program even calculates areas under the curves - which was what I used it for.

Purchase immediately!