What does the Department of Commerce do?

So Obama is nominating Bill Richardson to be Secretary of Commerce. Well, Richardson has a lot of cabinet experience, and this is good for the whole team of rivals motif, so, great! Of course, it would be helpful to know what a Secretary of Commerce does if we're going to evaluate Richardson's fitness for the job.

True story: When I worked at the White House, I was in a quarrel with some relatives about what exactly room temperature was. I thought it was 72˚F, someone else thought it was 68˚F. So I figured, hey, I work for the federal government; I must have access to the truth here, right? So I browsed through the federal directory and found the Weights and Measures division of the National Institute of Standards and Technology, which is housed in the Department of Commerce. I put in a call to a scientist there and asked what room temperature was. He said that that was not his jurisdiction and suggested I call another scientist there who was "in charge of boiling point and freezing point." So I got that scientist, who told me that there was, in fact, no scientific measurement of room temperature. It's just a convention, usually ranging between 68 and 72.

I love that there's a federal scientist in charge of boiling point and freezing point. You don't want to outsource that job.

Anyway, that was my first ever interaction with the Department of Commerce. My other one has been to frequently download economic performance data from the Bureau of Economic Analysis. I greatly appreciate having access to these data, although I imagine the Department of the Treasury could provide this service just as well.

I know Commerce handles trademarks and patents, which are a good thing. But again, could that be run by someone else? Labor? Treasury?

For all the libertarian talk out there about eliminating such agencies as the Department of Education or the IRS, why does no one talk about Commerce?