We skipped the last couple years and only sent them out to the people that we received a card from the previous year. It seems like each year we get less and less. I think that's because of the internet and people are in touch more often and don't feel the need to mail cards.
We haven't sent cards through the mail in years. My wife sends online messages to close family members that we don't see often. We usually see extended family at Christmas so we stopped sending them. It was a waste of money and we always had to make sure they were in the mail on time.
We don't send out Christmas cards. Sometimes we will print out pictures from the past year and give them to our relatives instead of cards. Cards can get expensive, especially custom ones. I'd rather give out pictures.
We send out picture cards so they can see how our kids have grown. Whether my wife and I are actually in the picture depends on the year; this year it's all of us together. Picture cards themselves are pretty cheap since we would be getting the pictures done regardless. We pay more for stamps than we do for the cards.
We have a set list each year and sometimes we add a few, other times we remove a few. It just depends for us because we have some family that moves around a good bit so finding a current address is easier said that done sometimes.
Cards aren't very expensive at all. My wife picked up several boxes at the end of one season for about $2.00 each and we still have a bunch of them. I do like the idea of sending out the photograph cards. We like when we get those. In fact, we still have one sitting on the bookshelf that we got last year from some friends.
You can always find good deals on cards after the holidays, most of the ones we send out this year are all from the purchases we made last year. Things are just cheaper that way and no one has every complained.