Typical Meteorite Crash Site
The Meteorite Meteor is the most common kind of meteor that you will come across. The crash site will be filled mostly with Meteorite Meteor blocks, but the crash site can also be accompanied by an Alien Creeper or two.
NOTE: Alien Creepers can spawn from the meteor blocks on a rare occassion so don't think you are safe once all the Alien Creepers around the site have been killed.
Resources
The most abundant resources you will gather from the crash site are meteor chips. Meteor chips are what allow you to craft the Meteorite Armor. Meteor Chips can also be dropped when the Meteor blocks are cool. You only get them about half the time though so it is not as good as mining them when they are hot.
The second resource you can gather from this crash site is Red Meteor Gems. They are dropped by the Alien Creepers and can be found in a Meteor Block on a rare occassion. Note that you must mine the block when it is hot in order to get the Red Meteor Gem(s) from the block or else you'll get nothing.