Originally Posted by Mr.Cairo
Another +1 on the ham radio and the SPOT, model with the texting ability.
The only other things I would add is a fresh, brand-new, clean high-visibility vest; a few smoke flares (they are available a boating/marine shops like West Marine) and toss in a few red road flares, which you should have anyway along with your first-aid kit. These items take up very little space and can always stay in the panniers.
Now the really important thing, just don't start a forest fire using the flares!
Neither my motorcycle nor my snowmobile survival kits contain any flares. I could think up a pretty big list of far more useful things that would weigh the same and take the same amount of space. I suppose if you're venturing off on a bike the size and weight of a small station wagon, you might not be thinking the same way I am...