Today, on the Strobist Surgery Channel...
Remember the chicken neck-breakin' version of making your SB-800 rotate around to 135 degrees in the other direction? Yeah, well, as of today that method has now been ruled Barbarian and out-of date.
Watch as South Carolina shooter Lee Morris shows you how to do it the civilized way -- and it is pretty darn easy. Being a smart guy, Lee sticks his portfolio in at the end, too.
Note that the video seems to load a little slowly, so you might want to let is play for 30 secs and then back it up to keep it going nonstop.
Again, the reason you really want this ability is not to be able to bounce a vertical, on-camera flash off of a wall behind you. But rather you want to be able to point the flash any direction and the CLS receiver (or SU-4 slave) in any other direction.
Same disclaimer applies: You break your SB-800, don't come crying to me. But I am going to try this method on one (and then, hopefully, all) of my '800's.
(You can see more of Lee's work here.)