OCRFeeder is a document layout analysis and optical character recognition application. It is able to automatically outline a document image's contents, distinguish between graphics and text and perform OCR over the latter. It can export to several formats, its main one being ODT. OCRFeeder has a GTK+ graphical user interface that allows the user to control the application and, for example, edit and correct the automatic recognition. It can also be used from the command line for automation.
PDF OCR is a simple drag-and-drop utility that converts PDFs and images into text documents. It uses advanced OCR (optical character recognition) technology to extract the text of the PDF or image. This is particularly useful for dealing with PDFs and images that were created via a scan-to-PDF function in a scanner or photo copier. It uses the Tesseract engine to perform OCR, and currently supports over 20 languages for OCR.
Paperless Office is a document management and electronic filing system. It is similar to Paperport, but adds many new features, such as automatic document classification, synchronization with your filing cabinet, date extraction, semantic Web integration, and sophisticated natural language processing, such as extracting todo lists from documents, spam detection, urgency classification, along with planning, scheduling, and execution features. You can set due dates and interdependencies for documents and tasks, so it has workflow support.
Solr-Connector-Files crawls and indexes directories and files from your filesystem (whatever is mountable to Linux) into Apache Solr. It features extraction of file contents with Tika, which extracts metadata and text form many document and file formats. It also integrates automatic text recognition (OCR) for images, photos, and PDFs using Tesseract OCR.
getxbook is a collection of tools to download books from websites. There are tools to download from Google Books' "book preview", Amazon's "look inside the book", and Barnes and Noble's "book viewer". There is an optional GUI written in Tcl/Tk, and some shell scripts using OCR to create plain text or searchable PDFs and DjVu files from the downloaded books.