is there any way to turn off the damn word completion?

[optimus prime]

I'm on mine right now and I hate it ......

[mavis]

Wirelessly posted (iTouch 1.1.3 (JB'd): Mozilla/5.0 (iPod; U; CPU like Mac OS X; en) AppleWebKit/420.1 (KHTML, like Gecko) Version/3.0 Mobile/4A93 Safari/419.3)

There is if you jailbreak. You can add a preference setting to enable/disable auto-completion under Settings/General/Keyboard ... ;)