Stealth - if you leave a parcel in your car, you shouldn't really leave it visible at all, in case someone breaks the window to get it - the annoyance & cost of that would probably be more than the value of the parcel.
I went to a conference on safeguarding children the other day, there was a guy from CEOP there who showed how easy it was to track down a child who put too much information on a social networking site, especially if they mention a school - very easy to go on Google street view and take a look round an area, then they can start talking to the child about it "yeah, I go to the school down the road, hang out at the chippie on Friday nights...." - makes it much easier to gain their confidence.
Children should only put nicknames online, age is OK, but not where they go to school or live, hobbies are OK, but not where & when they go to do them, or what they are doing at the weekend (if I put 'see you at the Forbury Saturday' you could find out which area I live in with a couple of clicks and if you have my photo, bingo!)
And another scary thing - more and more photos found on sex offenders' computers are self generated - those 'sexy' poses that 1 in 4 14 year olds have sent to a friend....
I'm pretty open on MN under this name, it wouldn't be difficult for anyone to find out who I am, but that doesn't bother me because I don't post anything I wouldn't like anyone to know.