I'll put it in laundry list format, to curtail my mental exhaustion.
1. Poetry system that ties in with any potential music system. LOTRO had an addon that implimented the syncing of lyrics and words and emotes with certain abc tracks. It was a player that came up with the addon, not the dev team, but the fact that the devs allowed for addons was what led to the innovation. The addon was known as poetical, if you're interested in looking it up.
2. Books add lore xp when read, depending on how many words/characters they consist of.
3. High skill in other areas in concert with high skill in calligraphy allows one to make skill books. Perhaps make it so that they can dictate to a scribe who can then record their words, so not everyone has to learn calligraphy. That also would put calligraphy in more demand as a service.
4. Once the amount of armors and clothing expands, maybe have a cosmetic system with cosmetic layers/dyes and so forth. Or at the very least a hide helmet option.