I realize Arena Net doesn’t pay a lot of attention to RPers but I’ll guarantee that many RPers would willingly purchase special emotes, such as /sit emotes (/sit1, /sit2, etc.) if Arena Net made them available on the gem store.
I am aware of other games that successfully do this and it would be a nice small addition to the game. It also gives Arena Net financial incentive to provide such things. In fact, an entire array of custom emotes could be unlocked via the gem store that way, for those that want them.