Lots of people have a lazy jack system on their boats and lots of people don't. Although I do not have lazy jacks on my boat, I have sailed on boats that did have them and they really made lowering the main easy.
You can buy lazy jacks for your boat or you can make them yourself. They can be expensive if you choose to buy them but they shouldn't be to hard to make some up for yourself if you want them bad enough.
Here is a great video done by Sailrite that demonstrates how to install Harken's Lazy Jack Kit. I myself am a big fan of Sailrite, if you are interested in anything fabric-wise for your boat check them out!
Here are few diagrams that should help you if you are in the market for a lazy jack system or if you want to make some at home.