[bazzargh]

Back in the 90s, this was done using Type 3 fonts (which have full access to the postscript language). This 1995 paper, for example, describes a technique for generative, random handwriting from samples. http://luc.devroye.org/mcdougallpaper.pdf

[jongalloway2]

Here's a very recent technique that renders an input string based on analysis of handwriting samples: http://visual.cs.ucl.ac.uk/pubs/handwriting/