90210 spawns you right next to a ravine...which has a 2nd ravine running perpendicular to it breaching its nadir...which in turn has an abandoned mine running through it at the intersect of the two ravines...which amazingly has a spider spawner at almost the exact point the 3 intersect (2 or 3 blocks off from being under sky).
X marks the spot.
Looking up from the spawner.
Looking down to the spawner.
I knew if I entered enough splash texts for seeds I would eventually find something interesting. Anyone feel like mapping them all?