I wouldn't be worried. I have three kids, and none of them talked before age 1 - and now my 5 year old is consistently getting extremely high marks for vocabulary and speech in his preschool. My 14-month-old daughter isn't saying any words yet.
If you're frustrated in trying to communicate with your son, you could try teaching him a little sign language. Just pick three signs or so (you can make them up, or look online for examples - try ASL - american sign language) and use them when appropriate (most folks start with eat, drink, and more). Once he starts using them back, add a few more (like help, cracker, milk, etc.)
The best way to encourage more talking is to talk to them. A one-sided running commentary about the day, in a regular speaking tone. The grocery is especially good for this ("let's see...we need some bread...I think that's in the next aisle, don't you? Yep, here we go - aisle 5. There's the bread. We're going to get wheat bread today - see? Let's put that in the cart. OK, what do we need next..." etc.)
If you're really concerned, check with your pediatrician. You can probably even call and speak to (or leave a message for) the nurse and she can tell you some warning signs to check for delays. They're good ones to talk to, because they see lots of kids every day and it gives them perspective on "normal" that a parent doesn't usually get.