Free OCR Tools

Optical Character Recognition, or OCR, is a technology to convert different types of documents, such as scanned paper documents, PDF files or images captured by a digital camera into text so that they are editable and searchable.

There are both free & commercial tool-kits.

Free -

1. SimpleOCR - 9.3MB application. SDK/Command Line versions are commercially available
2. InstantOCR - web based OCR
   
3. OCR Terminal beta - web based OCR, converts TIFF, JPEG, GIF, BMP formats to .doc, .txt, .rtf, .xml formats; PDF to Word

Free, Under development -

1. GOCR
   
2. Tesseract
   

Commercial OCR Toolkits -

1. ABBYY FineReader
   
2. OmniPage
   

Also see:
Experimental OCR feature to create editable Google Documents from high-res images
HOW TO identify a Font