The first web browser, WorldWideWeb, was developed on the Nextstep platform. Some features and keyboard shortcuts now commonly found in web browsers can be traced to Nextstep conventions.
The basic layout options of HTML 1.0 and 2.0 are attributable to those features available in NeXT's Text class
Makes you wonder, if the NEXTSTEP APIs directly influenced the web (history lesson: NEXTSTEP was the OS that became Mac OS X), how much of the future of the web will directly be based on the technology and design patterns used in the iPhone OS?
You laugh, but a lot of HTML5 (canvas, css animation) already comes directly from the Mac OS X APIs, where they were implemented first.
Food for thought.
Related reading: Joe Hewitt's thoughts on the state of the web