DM/DAM software solutions have powerful capabilities to do both, but an easy way for clients to experience both revision history and OCR is to use Google docs.
Google Docs has a revision history pane that allows you to view at a glance all changes made to a document by each collaborator. While it may not work exactly like a track changes tool, Google Docs revision history lets you view and revert to earlier versions of your doc, and see which collaborators made edits to each of these versions. Just touch ALT + CTRL + V to see the history.
OCR lets you convert images with text into text documents using automated computer algorithms. Images can be processed individually (.jpg, .png, and .gif files) or in multi-page PDF documents (.pdf). These are some of the types of files suitable for OCR. [Note: for PDF files, Google Docs only looks at the first 10 pages when searching for text to extract.] Good tutorial on how to OCR using Google docs is here.
While these tools would not be appropriate on an organizational scale, they are good examples of how OCR and version control could work as part an overall document management strategy.
What tools are you using to increase collaboration and the value of your organization’s assets?