IndexDB is a great website that has aggregated numerous different indices in use for remote sensing. It has organized them by wavelengths, band numbers, sensor type, etc. and even links to appropriate literature describing the index. It is an incredible an invaluable resource when performing indices on different datasets and can be useful to help guide someone to create their own index, or to possibly tweak an index that has already been developed by someone else.
I used it to guide me in creating a custom index for usage with a Blue/NIR NDVI filter, for instance.