If you are thinking of coding an OCR program from scratch, reading up on techniques may be useful. I found an OCR Survey from 1996 which reviews some of the popular techniques from a decade and a half ago. Reading that might be helpful; track down papers it cites or papers which cite it.
Usually the process goes as follows:
find text
find characters in the text
extract features from the characters found
do pattern matching
report suspected character
While getting a user to annotate text is fun and exciting, finding a collection of handwriting which is already annotated might save you a lot of time, that way you can focus on the nuts and bolts of doing OCR rather than building your own database of annotated text.
To start with a slightly easier task you might want to consider building a system to detect handwritten digits. The USPS produced a corpus for developing systems to do this for zip code processing. The link was something I found with a quick search.