About blocking the aisle with a shopping cart--here's a new thing I've noticed, the people who block an entire shelf as though they are guarding it while they alone are browsing its contents. This happened to me recently in the greeting card aisle. There was some holiday coming up - V-day maybe - and this woman had maneuvered her cart so that she was the only one that could access the entire section of holiday cards. And unless she was deaf, she ignored anyone who said "excuse me" so everyone else had to just wait for her to pick out her card.
It's happened in other places too - say, in front of all the soup cans, or all the steaks in the meat dept. - I swear these people are deliberately placing their cart so as to block competition while they make their selections.
Ah, never mind me. I just hate people. There are just so damn many assholes out there it's hard to bitch about just one group or action.