When I was little I used to think it was a bit weird that my nickname was Nick!
Nectar - my sister couldn't say my name when she was little so it sounded like Nicta or something and then from that Dad started calling me Nectar.
Nic/Nicky - kind of obvious!
Nichola with the ch actually said rather than like Nicola. I've had this from a few people over the years.
Nuc - Richard who I used to work with started calling me this because he's British and said it's how I sound. Ros (who appeared in a post below) calls me it too.
Crash - at work because I keep falling over and getting hurt.
Nicholas - get this at work. Some people at work think this is my name so some others at work started calling me it to try to encourage others to be confused.
Hutch - had this from a few people over the years but mostly from my friend Alan and Martin at work in London.
Dot or Ethel (as in the two in Eastenders) - Alan used to say Amy and I reminded him of Dot and Ethel because we could talk all day about nothing.
Niko-chan/Nikobi/Nikoniko - my flatmate Kimie used to call me these. I think Niko chan is the smily face picture thing. Nikoniko is like a sound for smiling.
Hutchinich - Andy (my bf from varsity) still calls me this sometimes - I think it was my log on for the computer at varsity or work maybe?
I know I've had more but can't think of them.