Many applications like databases front-ends and spreadsheets require that the user transfers data into their computer from a piece of paper. This is a problem because their user cannot look at both the computer screen, keyboard, and paper at the same time. Users will end up longer from paper, to keyboard, to computer screen just to enter one value.
The application can use speech recognition if the data is specific enough. While speech recognition cannot effectively be used to enter names, it's very good at entering numbers and selecting items out of a small (less than 100) list. Some recognizers can even handling spelling fairly well. If an application uses speech recognition, the user no longer has to look at the keyboard. If this is combined with text to speech then the user doesn't even need to look at the screen, and is able to focus on the paper.
Furthermore, because speech recognition is not as "modal" as a keyboard, some applications don't even need to require a specific field to have focus. If the form that is being filled in has fields with mutually exclusive data types - one field allows "male" or "female", the other is an age, and the third is a city - then speech recognition can hear the command and automatically determine which field to fill in. After all, if only one field accepts "New York City" as a valid entry and the user speaks "New York City" then the application knows which field to fill in.
Speech recognition can significantly speed up data entry.