We have two cell phones and a landline. We have thought about dropping the landline. However, we have two kids at home who might need it. So instead we are planning on dropping the options: call waiting, caller ID, voice mail. That will drop the cost almost in half.
I think it would be interesting to not have a landline. But as my hubby pointed out, there's not a 911 where they know where you are with cells. For the boys, I think that's important right now.
Reader's Digest says that 5% of those owning cell phones have unconnected their home phones.