Haven't looked into the subject too much yet, but found this a few weeks ago, and I think it is a really cool solution for maximizing immersion (albeit funny :D):
http://www.gamasutra.com/view/news/270704/Dev_makes_VR_more_immersive_by_sticking_Vive_wand_down_pants.php

Cockpit based games (like car racing) are nice because they don't have to solve the movement problem :) You just make the player (mostly) stationary within a fixed cockpit, and allow them to drive this vehicle.

First person games where you can get in and out of a vehicle would work. You could write an in-game reason why you can't stray from your vehicle... e.g. you're on Mars, the vehcile holds your oxygen, and you're tethered to it :D

I wonder if something like a jetpack could work -- moving using thumbsticks while jetpack'ing might feel ok.

For games that are less avatar-based and more floating-camera-based (e.g. an RTS), I'd expect the "scale gesture" (e.g. on a phone, pinching / moving two fingers apart) to become common. You'd "grab" with both wands and move them apart/together to scale the entire world and zoom yourself out. You could then "grab" with one wand to move the world underneath you, and then zoom back in over a different area.

For first-person based free-roaming games, I'd expect a lot of them to be confined to a 1x1m to 3x3m play area :lol:
Old arcade shooters (e.g. Time Crisis, Virtua Cop, House of the Dead) would work pretty well for this. To move between areas, there could be cutscenes of the player getting into a vehicle, which then delivers you to the next area - getting around the small play space restriction.

I've played a large-scale first-person free-roaming shooter -- they'd rigged up a tracking system that covered a whole warehouse floor. To allow you to explore massive game worlds, they broke them up with checkpoints of different types. One of the most effective was an elevator -- you walk into it, the doors close behind you, you turn around and wait, the doors open and there's a new area there. As long as the play space is big enough to cover a room and the elevator, you can explore a vertical building.
The other kind of checkpoint they used was for open areas. These ones would fade your screen to black, rotate the world by some angle (e.g. 90º or 180º) and then fade back in. It was a little disorienting at first, but you quickly got used to it. This kind of checkpoint allowed you to explore massive winding complexes, while in real life you're just pacing back and forth in a straight line.

In smaller play-spaces, this probably won't work though, as a checkpoint every 2m will get really annoying....

but afterward I had mild nausea that lasted until the next morning.

That's motion sickness / "simulator sickness". Even in games with good movement systems (e.g. gently walking around a 1m square), you can get it very easily if there's too much latency in the VR system (or other subtle imperfections).
It's almost inevitable with the Oculus DK1 -- I can only use it for maybe 20 minutes even in gentle simulations. The Oculus DK2 is a lot better but not perfect, and the Oculus CV1 / Vive are worlds ahead again.
Your nausea could just be down to the VR headset you were using :wink:

"Budget Cuts" has you teleport through a "portal sphere" (first you get a sphere to look around the location, then you can actually teleport there). Somewhere I read that this transition felt really natural, I assume because you can see where youll end up and can smoothly transfer through the "portal". Instead of everything you see abruptly just changing in an instant.

In hover junkers they said having the platform as a visual anchor point was really important. I assume to the player it feels like the world is moving, instead of the vehicle moving?

For mobile VR, walking-in-place input is most immersive, doesn't rely on a controller and can minimize motion sickness. My startup just launched a plugin for Unity called VR-step that adds walking-in-place input to any mobile VR project.

If you want to try it out we developed a free (no ads) game called Gravity pull for Android/iOS

Let me know what you think.