I've tried a few LED lights, but so far nothing has really clicked for me. I'm still more comfortable using an SB-800 or SB-600, or a combination of off-camera flashes (usually my favourite SB-26's).
That said, I continue to see some great work done with LED lights. Folks always have their favourites, and I've seen everything from deerlights from the hardware store to expensive, designed-for-photography lights like the LitePanels.
Check out this article by Philip Hinkle at EventDV.net where he compares the new TorchLED TL-50 with the LitePanels LED Micro and the Sony HVL-20DW2.
In the Field: Switronix TorchLED TL-50
