Dolphin Browser HD has been the browser of choice on my HTC EVO for a long, long time. It has features such as gestures, which enable you to draw a shape to perform actions; tabbed browsing with an upper limit of tabs I've never reached; and now Dolphin Sonar, which allows you to tap or shake the phone to place it into listening mode to bring up a voice search assistant.
For those using Iris, Evi, Dragon Go, or many of the other Siri-emulating clones, you've already had some of this functionality for a while from your home screen. But with Dolphin's Sonar, you have voice search just a shake of the phone away.
With the newest release, the browser also moved the Webzine functionality from the main program to an add-on, speeding up Dolphin and lowering its memory and storage footprint.
I'm not sure what speech recognition engine is being used, but it seems to understand my jumbled up tech mumblings fairly well, and the response time is superb.
There's not a lot of documentation on what this can do and it's a highly Google-centric search, but there are commands such as "twitter" to open the twitter home page, "new tab" to open tabs, etc. You'll have to discover some things on your own until a complete commands list is released.
Although I don't think voice navigation is a game changer, I think that's probably because Dolphin already won the third-party browser game. Even if you have a keyboard with voice integration already, this saves several steps. And if you're not currently using Dolphin as your browser, you might want to look again at it.