Part 1 on my series of scientific software underdogs!
Thanks to Descartes, most publications show graphs of results, but no data. Of course, the corresponding tables would take lots of paper space. (Lately, many journals offer free additional online repositories for this sort of data, but this good idea seems to be catching on rather slowly.) Anyway, g3data is a simple utility to grab data from graphs.
Usually, you take the graph from a scan or capture it from a pdf file; then, you still need some previous cropping using photo software (e.g. the gimp) — which could also be used to grab the data, by looking at the coordinates and converting. But g3data simplifies this a bit. It also works with skewed graphs (e.g., from manual scans) and logarithmic scales.
A similar solution: getdata graph digitizer