This may seem trivial, but I have recently been set straight on this matter, so I thought I had better bring it up. The word "data" derives from the Latin dare, which means "to give." In Latin, though, "data" is a plural noun and "datum" is the singular. I have traditionally busted my students' chops on this and insisted that they treat "data" as a plural noun: "The data are all entered," "Data are exciting," etc.
However, I recently came across a rather lengthy discussion on this point by astronomer Norman Gray. In his article "Data is a singular noun," he argues that the word data is no longer used in English in the same way that it was in Latin and that it is functionally singular, in the same way that "stamina," and "agenda," two other Latin plural nouns, are used. He further makes the point that in no case does it make sense to give a number to the plural. That is, one would never say, "here are five data."
Gray has much more to his argument and he refers to others who posted on the same topic with largely the same conclusion. The result: In English, "data" is a singular noun.
I am sure that Star Trek'sData (above left and himself a singular noun) would agree. And that his evil twin Lore (above right and also technically a plural noun but a singular, fictional being) would not. Or maybe it's the other way around....