I know we have math characters at this site, but not a fantastic collection, but here are some math characters you can copy and paste whenever you are writing down equations.

√ ·

α · β · γ · δ · ε · η · θ · λ · μ · ν · ξ · π · ρ · σ · τ · υ · φ · χ · ψ · ω · Δ · Λ · Ψ · Ω

∂ · ∑ · ∞ · ∫ · ≈ · ≠ · ≡ · ≤ · ≥ · < · > · ± · ² · ³ · µ · ћ · ±

I know we have many of these characters, but notice the squared and cubed sign, the plus-minus sign - hbar is also in there. This small change can make equations look so much more delightful:

without

(I might write) G(∫ ∏_(n=1)^3 E^2/c^2 - |p^2| = Gd^3v^2(\hbar (c/G))d^3t

Using those added symbols, it looks quite a bit better (note, the dots are just lining in the upper and lowercase numbers (n=1) and 3 (space dimesions:)

......3

G(∫ ∏ E²/c²-|p²|)=Gd³v²(ћ(c/G))d³t

.....n=1

It makes it much more cleaner to read. So they are there if you need them.