I have always said that the major reason to avoid geo-location technology such as Foursquare is that it advertises the fact that your house is probably empty and ripe for a visit from the local burglar.
Most people get annoyed by Foursquare updates anyway, but actually Twitter and all sorts of social media can use geo-location technology too so need to be careful
Now some crafty chap has created this handy tool to drive this point home: http://pleaserobme.com/ This online tool is both amusing and fear inducing at the same time. I expect to see this website in the Daily Mail tomorrow.
(thanks to @fernandorizo for the tip)