As others have said, "data" is often used these days as an uncountable noun, either in the singular or plural. However, it is still also used as the plural of "datum". This answer is just to show that "datum" is also still a part of English, provoked by another answer that strangely claims that it isn't. (Too long for a comment.)
Looking through Google News gives, from recent news results:
The most interesting datum to me in the National Journal/Pew poll is…
…a superficial news item about one datum.
"… with a single datum, you can’t say anything about…"
…going to define the datum from which Mahindra…
God defend us from a man of one datum, particularly if that man is an economist, and particularly if the datum is wrong.
…a capacious but intricately ordered narrative that in its majestic sweep seems to gather up every fresh datum of our shared millennial life.
Of course, as the authors of the article are quick to point out, a crucial datum is missing: the percentage of all published fiction written by men versus women.
Researchers in some labs are irresponsibly subjective in their analyses: any turn of the head is counted as a positive datum.
All these (and many more; I got tired) in a span of two weeks. Among these publications are national and local newspapers, student magazines, and blogs. There also appear to exist standard phrases like "poverty datum line" and "chart datum level" (of rivers). Of course, there are also plenty of occurrences in the classical literature. (It occurs several times in the Sherlock Holmes canon I read as a child. :-))
Sure, "datum" not the most common of words, but claims that it's not a part of modern English, or that you need to wear a toga to use it, seem unjustified.