Other noisy things artists bring.
People have a habit of turning up with things like accordions (annoying to mic, as sound comes from both sides of it) or the magic singing iguana.
Strings & Brass
To warm, boost 300-400Hz slightly, while knocking -down top end. To brighten, boost 6-10Khz (ish) to generally pull everything together, cut 1-3.5kHz slightly.
Much debate over how to mic a DB, esp. in Jazz situations, most popular so-far is wrapping a 57 in thin foam and wedging in between the string arrest (big black thing strings tied to) and sounding box (body of DB). Otherwise treat like a big acoustic guitar, with a bow and put a 57 on a stand nearby.
ideally need at least two mics, because pianos are BIG (PZM on the floor underneath is popular if the floor is solid), but, with synths being popular most of the time you deal with a DI or two. Again, attack at 4-6kHz; warm the bass with boosting 90-150Hz while boomy noises come between 250 and 350Hz. HOWEVER mic positioning is of utmost performance, if the sound sucks, it's unlikely the fault of the pianist, as they can't altar the tuning or dynamics of the thing itself....