US: Anger and frustration and a level of politeness. The person who says "I need for you to come here" is angry and close to losing control. The extra words into the sentence are a show of hyper-politeness to emphasize the frustration underneath the command. I would go there quickly. The person who says "I need you to come here" is being more direct.

Interesting question, Gavin. There isn't any difference in the meaning, but there is in usage: 'I need you to come' is more usual, certainly in British English. I'm not an expert an American English, but I think 'I need for you to come' is more common in the United States. Helen

both mean the same, but the first (I need you to come) is the better way to say this. The other one has needless words