there not nicknames, there suffix's and general terms of respect.
-san is is the most common honorific and is a title of respect. It is used for the surnames or given names of both males and females. Although in translation san is usually rendered as a common courtesy title like “Mr.” or “Ms.”, unlike these it is never used in self-reference. Using san to refer to oneself makes one appear childish.
-kun is an informal honorific primarily used towards males (it is still used towards females, but rarely). It is used by persons of senior status in addressing those of junior status, by males of roughly the same age and status when addressing each other, and by anyone in addressing male children. In business settings, women, particularly young women, may also be addressed as kun by older males of senior status. It is sometimes used towards male pets as well. (i should point out here, that it is concidered a strong insult when -kun is used on women in a normal setting. because it means your looking down on her, when your not really above her)
-chan is a diminutive suffix. It is an informal version of san used to address children and female family members. It may also be used towards animals, lovers, intimate friends, and people whom one has known since childhood. Chan continues to be used as a term of endearment, especially for girls, into adulthood. Parents will probably always call their daughters chan and their sons kun, though chan can be used towards boys just as easily. Adults may use chan as a term of endearment to women with whom they are on close terms. (also should point out here, least you know the guy and mean it as a joke, don't ever call a japanese guy -chan...he'll likely kill ya)
-Sama is the formal version of san. This honorific is used primarily in addressing persons much higher in rank than oneself and in commercial and business settings to address and refer to customers. It also appears in words used to address or speak of persons or objects for which the speaker wishes to show respect or deference, such as okyaku-sama (customer) or Tateishi-sama (a stone idolised as a deity).
There is also Senpai, which are used to people who are older and experienced in a particular field, and Kohai which are basically newbies under the Senpai. An example would be if i started a boxing club, i would automatically be the highest senpai, and everyone under me would be my kohai.
you can find others here -
http://en.wikipedia.org/wiki/Japanese_titles - but that list doesnt include all of them. there are still a few that i don't remember, and a fair few that i remember and havent learned yet.
~Zeke~
oh man now you made me put up my ingame sig 
and dont laugh either cos i started playing again two weeks ago 
)
but there are so many Japanese customs that are hard to get my head around)
