months late to the discussion, but what the hey...
I tried the "just add a USB extender cable to the iphone cable" solution.
Looks good on paper, but it's the WRONG answer to the "I need a longer iphone cable" request above.
Why? Instead of a very diminutive cable, you now have:
1. The weight of the usb male & female connectors inline
2. The weight of the (probably) thicker cable (mine was double the diameter)
3. Compounded by 4 to 6 feet of this now thicker heavier cable
It's ungainly and sloppy - doesn't tuck away easily in any non "behind-the-desk" area. The weight plus the connectors inline can knock things around on a desk, and the inline connectors can catch on things.
The orig cable is actually quite thin and wispy - I forgot that until I connected the big-ass transatlantic usb extension cable.
I don't think it's anyone's fault that I can't find one, but for the sake of the (long dead) discussion, although a usb extender really does look good in theory, a simply "longer iphone cable" would clearly serve the need much better.
And yes, I'm too lazy/busy to make my own.
