Firefox was first to popularize tabbed browsing and first to integrate pop-up blocking, spell checking and antiphishing into the browser.

FORBES: Magazine Article

It looks great and while it does not have the functionality of, say, Microsoft Word, you can do things like automatic spell checking as you type as well as insert tables, images, and lists.

BBC: NEWS | Programmes | Click | Webscape

The idea grew out of their effort to market a medical spell-checking program over the Internet.

FORBES: What the doctor ordered