I agree with Ben's answer, but think the question is a little simplistic. You always have to consider total revenue as well as margin, as profits = margin x sales.
So a company may choose to go low margin if it means there are more sales there so overall profits are higher. For example a Ford focus will be low margin Vs a Ferrari, but you'll sell a million Fords for every Ferrari so probably worth it overall.
In terms of other examples I would look at cars again. Some cars will produced at no margin, or at a loss, but will "Halo" over the rest of the range making them more prestigious. For example a company like Aston Marton might do a special edition vehicle that is at the top of their range and low margin, as they'll get publicity from it which will increase sales at the lower of more affordable and higher margin cars.