On several short w/e trips earlier in the year I carried around a relatively heavy chain whip in case of rear spoke failure. One day, after one of these little jaunts, I realized I carried no cassette lock nut tool. One without one the other is useless so carrying the whip was weight I didnt need. On the longer summer tour I didnt bother with it, hoping that the spokes would survive. They did.

On the longer tour I carried an MSR water filter. Never used it. I guess it is fairly important but when you are riding thru civilization good water is generally close at hand. Some tablets would have don the trick jsut as well.