First off, read that last sentence again. I'm apologigizing for what I'm about to say, and pre-emptively hedging. I often find myself wanting to make an extensive disclaimer before I weigh in on charged subjects, just in case
Another thing is questions. There was a day at the looney bin when I was forbidden to ask questions (thinking about this pisses me off, but is not the point), and it brought my attention to how often I do. Not just as requests for information, but as alternatives to, say, commands. "Could you do x?" as opposed to "please do x". Once again, it feels rude to use the imperative. And "would it be possible to y?" rather than "we should do y". It's hedging again, I think, and it also leaves the other person the opportunity to say no. It's like I'm building in a grammatical method of shooting me down -- it would be ruder to say "no, we shouldn't do y" to the latter than to say "no, it's not possible" because, well, that's a valid answer to the question. And really, thinking about it, I classify statements as a more male way of talking than questions.
Upon a secondary google as I write, I find the following on tag questions:
"Lakoff (1975) observed that, in certain contexts, women use question tags more frequently than men do. She defines the tag-question as 'a declarative statement without the assumption that the statement is to be believed by the addressee: one has an out, as with questions. [The] tag gives the addressee leeway, not forcing him [sic] to go along with the views of the speaker.' (Lakoff 1975:16)" (from this site)
[An actual definition of tag questions is that they're those little, two-word questions that one tacks onto the end of a statement: "You are coming aren't you?" "It sure is wet out, isn't it?" "He can do this, can't he?"]
Evidently further studies have been contradictory on which gender uses tag-questions more, but I would tend to agree with the bit I quoted above on the general motivations behind this kind of language.