I know there are more than a few wordsmiths among our readers and this entry is for you.
Data is a troublesome word. It is the plural of datum. And yet, I find it unnatural to say "here are my data" instead of "here is my data". Similarly, "datum point" is more grammatical than "data point" -- and perhaps both are redundant words -- because we should use a singular noun to modify another noun (e.g. company ranking, not companies ranking; potato chip, not potatoes chip; etc.)
In a recent piece on RSS News, Ian Schagen convinces me to treat data as singular, without remorse. Among his many arguments, he points out that agenda is the plural of agendum and yet we have no qualms using agenda as singular. So from now on, data is singular.
Ian has the last word:
In fact an amusing pastime is to read papers and articles by people, trying to use 'data' as a plural because they believe this to be 'correct', who slip into the proper English usage when their attention wavers. I've often seen both usages in a single sentence!
Source: "Why 'data' is singular", RSS News. (Unfortunately, this seems to be only available to members in paper copies.)