Just in case you weren't satisfied with that "customize a pony" game from earlier (Which 403'd for some reason even though the link works for me!), the Finnish MLP website has another one for you to try out. It is essentially the same one the US MLP flash game has, but in this one your OC pony gets to hang out with the mane cast in some random scene after creation.
So far I've seen..
1.) Bathe with the Mane 6
2.) Party with the Mane 6
3.) Buck Apples with the Mane 6
I am not sure if there are more!
Anyway enjoy, its stupid short, but mildly entertaining.