Boston Globe: Boston Public Library asks for help in transcribing abolitionist letters. William Lloyd Garrison’s letters are among the more frequently consulted collections in the Boston Public Library; this project seeks to make them accessible and searchable over the web. This is a rare opportunity, in this world of Google Books and OCR, to help to digitize an asset the old fashioned way. You can sign up to help at antislaverymanuscripts.org. The effort uses the new-to-me Zooniverse platform, which enforces not just crowd sourcing but also crowd-correction: no transcription is accepted unless three volunteers provide the same transcription.
I did a bit of book transcription when I had my first Internet-facing job in 1994, as an undergraduate in the Electronic Text Center at the University of Virginia (now absorbed into the Institute for Advanced Technology in the Humanities), but most of what I worked on was marking up and correcting texts transcribed by volunteers at Project Gutenberg. Crowdsourcing digitization goes way back.