If you are using any alternative PDF viewers like Google Docs Viewer or Sumatra Reader to get away from Adobe Reader bloat - you might land on an error as shown below when trying to read some PDF files.

After adding support for 12 new file formats in Google Docs another update to the service now brings optical character recognition (OCR) to 29 additional languages (making the total supported languages to 34), the free online OCR feature allows users to upload photographed or scanned documents and convert them to editable text documents.