Shear Force and Bending Moment Diagrams: This website is useful because it explains point loads and point moments. It also explains step by step equilibrium moments and forces, and it gives you a brief example of them and how to derive/draw shear forces and bending moment diagrams.
Bending moment calculator is specifically used for computing bending moment and shear force toward load that differs consistently with various intensities (highest on left side) on simply supported beam.
Shear Force and Bending Moment Diagrams: This is a good website, provides a great deal of explanation for the formulation of equations. Displays the diagrams that correspond to the different loads and forces; this allows you to select the most appropriate equation. It also explains shearing force and bending moments.