Infinite line charge (lambda): Cylindrical Gaussian surface of radius r, length L. Flux = E(2pirL). Enclosed charge = lambdaL. Result: E = $\frac{lambda}{2*pi*epsilon_0*r}$.

Infinite plane sheet (sigma): Pillbox Gaussian surface. Flux = 2EA (both flat faces). Enclosed charge = sigma*A. Result: E = $\frac{sigma}{2*epsilon_0}$.

Two parallel infinite sheets: Same sigma: E = $\frac{sigma}{epsilon_0}$ outside both sides, E = 0 between them. Opposite sigma (+sigma and -sigma): E = $\frac{sigma}{epsilon_0}$ between them, E = 0 outside. This is the basis of a parallel plate capacitor's uniform field.

Infinite uniformly charged cylinder (rho, radius R): Inside (r < R): E = rho*$\frac{r}{2*epsilon_0}$. Outside (r > R): E = $\frac{lambda}{2*pi*epsilon_0*r}$ where lambda = rhopi$R^2$.