I've been looking at gaming keyboards to use on Ubuntu system.

Microsoft has a few popular ones (e.g., Sidewinder X4, X6), but the programmable function keys appear to be unusable without the Windows software. (Though here's a post from someone who has a more recent project that uses usbmon and xdotool to add functions to some keys.)

Another choice in my budget is the Cyborg V.05. It seems about right for my needs, but I would be depressed having a bunch of useless, nonprogrammable keys on it.
Logitech has some models (e.g., the Logitech G110), though again I expect that the extensive macro capabilities (which I don't need) would be lost under Linux. There's a project called g15tools which has some code to work with older Logitech gaming models, but I don't know what the current status is. Last entry there was in March 2010. There are also a number of very old posts around the internet with regard to the Logitech G11 and G15. Compatibility with the current keyboards, Ubuntu version, and Linux kernel are suspect.

I'm in the U.S., and so it appears that few of the Roccat keyboards are available, and they're over-priced. Support might be OK for these, though -- there's a short Phoronix article about Roccat improving their Linux support, and there's also a project and webpage for "Using Roccat Hardware with Linux".

Honestly, the only feature I have to have is good backlighting for the keys, and if it's not wired (which is fine), the wireless capability should function. I could probably live with dead function keys, as long as they weren't in places that would interfere with things like Unity/compiz shortcuts.

Any experience or suggestions?

I've not seen much to inspire confidence with programmable/macro keys. There is a thread (with no solutions) on the Sidewinder X4 on ubuntuforums here.

I'm also considering the Logitech Illuminated Keyboard as a possibility, even though it's not specifically a gaming keyboard. It is backlit, and it's supposed to be a nice keyboard.