While I don't use them that way, I understand that they operate in stand-alone mode (I use them in PS/CS6). A lot of the capabilities in Nik collection were first published in Capture NX. It would not surprise me that the capabilities of NX2 envelop many of those you see in the Nik collection (probably not all though). Sine I have sold most of my Nikon stuff, I don't use NX2 much anymore, but I do still use it now and then. It is still a powerful tool.
If you have the Nik collection, try opening them alone and see what happens.
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Oops, I see that you are writing "NIC" now and I am wondering if you are talking about somebody else's tools (although I can't imagine that they would use the same names like has also been mentioned ("Color Efex Pro")!