J C said:
なんか is used after a noun or a noun-ised verb (e.g. 行くこと) to emphasize that something (usually the noun/verb it after) is causing some sort of trouble for the speaker. It adds an exasperated or derogatory tone to the sentence. Very difficult to translate as any specific word in English. Usually you can switch the なんか for a particle (は、が usually) and it'll still be grammatically correct.
Used before an adjective it can be translated as "... or something" but again it adds the derogatory tone.
Do an example search at WWWJDIC on "なんか" for some examples.
I think this is more a spoken construct than anything you'd see in formal writing - someone correct me if I'm wrong here.
なんて adds emphasis to the sentence, but is different to なんか. It comes before the thing you want to emphasize. Before an adjective it could be translated as "very" or "how ..."
I'm not 100% clear on this, so if someone can correct me, please do.
Below is what I wrote in another thread a year ago:
""nande" is not the contraction for "na no de" (because), rather, it is a contraction for "na no desu" (de is the -te form of desu)
"nande" can also mean "naze", which is exactly the same meaning as "why". "nande" becomes "why" only when placed at the beginning of the sentence.
ex. "nande gakkou ni ikanakatta?"
Why didn't you go to school?
There is also "nante", which sounds similar to "nande". Although they sound similar, the meanings are quite different. Nante is a little bit more advanced, but is often used in colloquial speech.
1) Nante utsukushii!
How beautiful! (used as an exclamation)
2) Nante can also mean "nado", or "things like"
yuuki nante moteba, nan demo dekiru (If you hold things like courage, anything is possible)
3) Nante can also mean "nado to ", and is used when quoting the phrases of someone else.
"arukinagara taberu nante mitto-monai wa. yamenasai" nante (itte) haha ni shikararechatta
I was scolded by my mother, with her saying that "it's indecent to eat while walking. Quit it!".
(Note that the first nante means "nado", and the second nante means "nado to".
There are also many other uses of nante, and some are quite advanced, so I don't want to get into all the grammatical details for now."
Also, for nara, you can use that after infinitive verbs. the formation is absolutely fine. sometimes they add a "no" in between (ex. taberu no nara) and it does not change the meaning.