The first 2 channels, Nickelodeon and Nick Jr, launched in 1996.
NickFlicks debuted in 2000.
NickToons launched in 2004.
TeenNick and NickPlus both launched in 2009.
NickTunes launched in 2014.
As for the programming blocks, Nick@Nite launched on Nickelodeon in 1996.
NickTurbo debuted on NickToons in 2011.
Also, as for defunct channels, Aquaria used to have channels for Nick GAS (1999 - 2003) and Nick Go! (2003 - 2009). Nick GAS was replaced by GO!, which went on to be replaced by TeenNick.