The Vivitar 283 is still a great flash. I use a Nikon SB-28; the newer digital-optimized Nikon flashes are also very good. I use Elinchrom skyport radio triggers to synch with off-camera flash - they're cheaper than pocket wizards & a lot smaller.
Here is an example of a photo taken with the M8 and an SB-28 triggered via the Elinchrom.