www.free-ocr.com is online service for text recognition. The recognition quality is good, even with a low image quality. It has a limit on the size of recognizable file of 2 Mb. It supports such languages as English, German, French, Spanish, Italian, Russian, Czech, Danish, Dutch, Finnish, Greek, Norwegian, Polish, Portuguese, Swedish, Turkish, and Ukrainian.
Service recognizes well a text from the image in which the text was printed on a computer. But with the scanned books it worked worse.
It should also be noted that the service does not support layout. If you recognize a text from the image that contains columns or captions, you will get a mixed text.