The word 会社 has a sense that I have often heard in conversation but seems to be noted in no dictionaries: "workplace." A person might say, for example, that she left something at her 会社 when in fact she works at a government office or for a nonprofit organization.
I haven't even tried to find Web citations of this meaning, as it is very context-dependent; one must know where the person works before concluding that 会社 means "workplace" but not "company," and such information is often not easily determined from the context. And, of course, 会社 usually does mean "company," making the "workplace"-only examples even harder to find. But "workplace" is not an unusual meaning of 会社 in informal contexts and should be noted in dictionaries.
(June 24, 2003)
This sense is noted in the fifth edition of Kenkyusha's New Japanese-English Dictionary:
かいしゃ１【会社】… 〔職場〕 one's workplace; one's place of work; where one works; 〔仕事〕 (one's) work.
One of the many examples given of this meaning:
新聞は会社の行き帰りに読む. I read the paper on the way to and from work.
(July 17, 2003)