When my girlfriend and I were first together she called me Kit, which is a nickname I got from an online friend (in return I called this friend Nissa, which is nothing like her real name) but which very few other people use. These days she calls me Chris.
I don't have any real nicknames. It would make sense, because we have multiple Chrises in myu social circles, but usually I get "Chris Adams" as opposed to "Chris Cook", "Chris Stabback", or whatever.
I have some great ones for people I know, though. My father's name is James, and everyone except his siblings calls him Jim - they call him Tim. My mother claims to have momentarily thought she'd misheard him for months when she met his family and everyone called him Tim.
My friend from high school Nick and I went to the same university, and in first year he earned the nickname "Boots" for acquiescing to the pick-up line "Nice boots, wanna . . ."
Many of my friends, especially those with one-syllable names, will be greeted as "The Dan!" or "The Kim!" My friend Georgia has been briefly known as Uzbekistan (geography joke!) and Genoriga. A surfeit of Andrews led to the most recent addition to the social circle by that name being dubbed "Percy", and we have a minor tradition now of giving people abstruse nicknames like "Thor".
One guy was nicknamed "Steve" because he looks like Stephen King and had a name that was already "taken". An Andrew came to us from his high school with the nickname "Spamy", which I understand was the nickname (possibly based on a surname) of an earlier Andrew at the school and got passed on to him.
Several people in my university gaming circles are known primarily by their SCA names.