WebPlotDigitizer - WebPlotDigitizer - Web based tool to extract numerical data from plots, images and maps.
Engauge Digitizer - This open source, digitizing software converts an image file showing a graph or map, into numbers.
GraphClick - GraphClick is a graph digitizer shareware for Mac OS X which allows to automatically retrieve the original (x,y)-data from the image of a scanned graphor fom QuickTime movies.
g3data - g3data is used for extracting data from graphs.
im2graph - im2graph graph digitizing software to convert graphs to numbers
Silkscientific UN-SCAN-IT - Digitizing Software converts graph image files to usable (x,y) data automatically