All are good for research papers: cite is short for citation, site is a place, and sight is what your eyeballs are for. The Web has a lot to answer for, good and bad. One item in the minus column is the increased popularity of site and people throwing these sound-alikes all over the place!

Cite is a verb to mean to quote, to summon officially, to mention formally, or even to compliment. It's also the noun form of the same things: a formal summons, or an official mention. You have to cite your sources when you write a paper, but it's also a nod to wherever you got your idea. Check out what cite can do:

The band, formed in Ohio 10 years ago, cite numerous influences in different genres from hip-hop to rock and blues. (Reuters)

He was taken to his residence in Bellevue, cited and released. (Seattle Times)

A site is a specified place, such as a building site, but it's also short for Website, which is a collection of Web pages that are found within the same URL. Either way it's somewhere you can go:

It's taken nearly nine years, but large-scale commercial redevelopment of the World Trade Center site is tantalizingly close to taking off. (New York Post)

The death also was reported on the singer's web site. (Seattle Times)

Sight, of course, is vision or something that can be seen. If something is outta sight then it's fabulous whether you can see it or not. Here's an example of sight:

Visually impaired servers who have some sight wear blindfolds. (New York Times)

Though cite, site, and sight were confused before the Internet, we are more likely to use site for all of them because we use it so often for Website. If you can remember cite is short for citation and site is a location, whether it's online or off, you'll have the sight to use the words correctly.