One of the things I love most about the concept of MLP is Cutie Marks. Being a typical 'girly girl' when I was younger, I watched all of the G1 and G2 stuff, including the movies. But it has only taken until G4 to realise the concept of a Cutie Mark. Before, I thought they were just pretty marks on the pony, added for decoration without any significance, which may have been their original intention for the toys, but now I see their true potential being slightly older and wiser. The thing I love about Cutie Marks is the fact they make finding your unique talent, and sometimes life path in the case of Cheerilee, refreshingly simple.
Don't worry Crusaders, I don't mean in getting your Cutie Mark. We've seen your struggle. But, the fact that this special talent is regularly realised at a young age, at least in what we've seen, is what makes it interesting. Most children will not know what they will be when they grow up, and will not find what they want to do until years later. Sometimes when it's too late, sadly. But, this idea of a visible mark on the body that will show you what your special talent is could be so helpful. A lot of people don't know if they're any good at something, and getting a cutie mark in something I reckon could be the biggest morale boost yet.
Of course, in the universe of MLP:FiM this concept can make a lot more sense. The talents most ponies have are pretty clear after meeting their character, think of the gentle Fluttershy when we first see her, directing her bird choir and obsessed with Spike, we could tell she was close to nature. However, there are some ponies whose talents don't make sense, like Diamond Tiara and Silver Spoon, whose only talents seem to be their ability to be stuck up? Either that or they'll become skilled jewellers specialising in Spoons and Tiaras. Unfortunately, you cannot always tell a person's special talent the first time you meet them. It is possible, for example, with musicians or artists, but otherwise you're completely in the dark.
Basically, I want a cutie mark :D I have no idea what it would be though.