Ask HN: Recommend solution for scanning forms?

I am working on an application where I need to collect data from lots of regular people. I am looking for an efficient, reliable, inexpensive alternative to "Scantron" (used for machine-readable multiple-choice exams)

I am hoping to use a Mac laptop with a portable scanner (http://www.fujitsu.ca/products/scansnap/s300m/) that scans pages to PDF.

I have complete freedom for how the data forms are designed, ... and I am looking for reliable (free?/open source?) software that could capture the data from the (scanned) PDF and save it to a text file.

If anyone has any experience with something similar, I'd really appreciate hearing from you. Any other links or suggestions would be appreciated too.