This is a great question, and I can't wait to read the other answers, too, which hopefully will come soon. We're not trying yet, but about 2 days ago, I had a dream in which I gave birth to a little girl. She was great!
The same night, DH dreamt (had to look that one up in the dictionary!) of a daughter, too. He woke after feeling in the dream disappointed--I've been trying to get to a target weight and then maybe go down just a tad more, then eat a lot of high calorie meals before TTC, because we read that can help your chances of conceiving a boy!
Being a first-born son, he thinks it's the way to go. However, I'm an equally stubborn first-born daughter, so that wouldn't be bad either!
Anyway, all that to say I'm excited to read more here of how to influence chances to conceive a son.