My wife--who is now 20 weeks along--had her 2nd ultrasound done last Friday, and although the baby seemed unwilling to cooperate with us at first, we finally determined that we're going to have a son! For some reason my instincts told me we'd be having a daughter, but my wife and the other ladies in her family all predicted otherwise, even her 5-year-old sister. Guess their 6th-sense trumps mine... [edit: my sister would like to make it known that she also predicted a boy. Carry on.]
We had no real preference one way or the other and are simply happy to know that the baby is apparently healthy so far. We have his name picked out already but we are still keeping it under wraps for the time being. The due date at this point is December 27th, so we may end up having a pretty awesome Christmas present :)
To save him some future embarrassment, I won't post the ultrasound proving that he's a boy, but I did find it hilarious that they labeled the photo "Boy Parts" with an arrow pointing right to the proof in case there was any doubt.