Sugru looks pretty useful but appears to be very expensive for what you get, could be useful for making my Mod4 Survival knife a little more comfortable around the guard though.

I have previously used Dow Corning 3140 RTV and 2 part epoxy to make some running repairs that have lasted. Many adhesives and glues are a complete let down and don't live up to expectations unless you know where to go.

http://www.youtube.com/watch?v=58zzs4hzEIg