Logs are very important, because there will be times when you'll want to know what happened.
I have owned four celular phones up to now, and I've always felt that they are very poorly designed (I'm sure I can quickly come up with a list of 10 flaws for each of them).
One feature that I'd like to see in celular phones are logs.
Suppose you send an SMS to someone. A couple of days later, you might want to confirm when and to whom you sent the message to.
This happened to a friend of mine yesterday. He was supposed to send me a message on Saturday night confirming whether we'd be going to the zoo on Sunday.
On Sunday, we spoke and he asked me about the message, which I said I hadn't received.
Turns out, he sent that message to a senior person on his family, who happens to be a very serious person.
The message:
Tomorrow you'll see your cousins at the Zoo.
