Invention: metal detecting shoes. These would clip onto the soles of a pair of shoes and they would function as the user walks around.
Art: a portrait of a human body where each part is coloured by a drug that works on that part of the body
Movies: an IMDB page showing films on today (this week) and their IMDB rating
Book: Larson's Far Side Choice. Cartoonist Gary Larson would compile a book featuring his favourite cartoons by other cartoonists. The concept could be expanded on, so that an expert in a field would give his favourite output by others in his field.
Website: honest advertising. A website would feature products/services being advertised in the media that week and for each product/service would give an objective account of the product with statistics.
The fake bullet. In a hostage situation where the 'baddie' has a hostage and is holding a gun to their head the armed officers fire the fake bullet to deliberately hit the hostage. The bullet is made of rubber and contains a red dye aimed to look like blood. The bullet also contains an agent (?) to make the hostage unconscious. When the fake bullet hits the hostage the 'blood' splatters everywhere and the baddie thinks the armed officers have accidentally shot the hostage.