I'm now using them for clusters of similar equations, so my index numbers don't get too outrageous.
\begin{subequations}\begin{align}
Y_1^{+1}(\theta,\phi) &= -\sqrt{\frac{3}{8\pi}}\sin\theta e^{i\phi} \\
Y_1^0(\theta,\phi) &= \sqrt{\frac{3}{4\pi}}\cos\theta \\
Y_1^{-1}(\theta,\phi)...