Neodymium magnets are extremely strong, as anyone who has ever handled them knows. This video shows how strong the forces generated by them are. One should be very careful though, because you can hurt yourself and any nearby electronic equipment with these magnets.
One of the practical uses of these magnets is to have cows swallow them. Yes, really. This is because cows often swallow bits of metal (nails bits of wore, staples, etc.) that are in the pastures where they feed and this can harm them. These powerful ‘cow magnets’ settle in a part of the digestive system called the rumen, where they collect the metal pieces that pass by and prevent them from going further into the system and causing harm.