http://www.knitty.com/ISSUEsummer07/PATTzodiac.html
I thought this was clever idea. The colors are based around the baby’s anticipated zodiac sign, so nothing to do with the sex. I think I’m going to make one when my wife gets pregnant.
And if you don’t want to do the zodiac sign, you could always leave that off and just have a brightly colored baby sack.
Get some cotton yarn and knit a bunch of diapers. you might start a new baby fashion trend. 
I didn’t know the sex of my first baby. But everyone else around me did! They did a good job of keeping things secret.
I have to admit to getting tired of seeing mint green and yellow, though. The idea of knitting a blanket in stark contrasting black and white patterns is a great one! You need something like that for baby’s “tummy time” to keep them interested and occupied.
The idea of knitting things to wear in white and navy blue is great, too. Wonderfully neutral but much nicer than pink or blue.