If you're thinking about one of these things - there is a pretty cool solution that I think works better with WoW. You might try looking at the Wolfking Warrior. I just got mine this past weekend and it seems pretty slick - a friend of mine introduced me to it. Takes a little getting used to, but I thought both of them did. I use the ~ for Smartbuff, and that's located at the bottom of it, so I might have to change the key if I can ever get Smartbuff to work during combat. But I don't think it'll be hard to re-learn the button position since it's pretty much the same finger config as a keyboard. I believe the biggest benefit it gives you is closer access to all of your numbers keys and function keys, which I think plays to WoW better than the current Belkin Nostromo n52te. There is no software for the Wolfking, it's just a USB Keyboard. It's pretty much a simple solution with little overhead, since you'd have to setup your keys to a keyboard anyways. I got mine for around $30 US shipped.

The Belkin does have some neat mode switches, a mouse-wheel, a hat-style thumb joystick and being backlit is just plain cool. It is more for the FPS games IMHO, as you don't need as much access to your number row. I have had some problems with the software under Vista for my n52te, so I don't have as much scripting built in like I did in my old FPS days. I thought about using it to dig deep into those modes, which can offer a PvE mode and a PvP mode and a Buff mode if that fits your playstyle - but it'll take some work. If I remember right, I believe you can set your keys to have an auto-modifier - ie. single button press could be Alt-<button>, Shift-<button>, Ctrl-<button> but I can't remember if you could use two modifiers on one key ie. Ctrl-Alt-<button>. I had troubles finding mine, then they unexpectedly stocked it in the Electronics Department at a local Furniture Store. It cost me around $75 US. It sits silently above my keyboard today.