Hi, The banks allow you to save different settings for different scenes.
You can "name" each of the Shooting menu and Custom settings banks, mine are :
A - General
B - Lowlight
C - Landscape
D - Sport
For each bank of each menu, you can set the controls as you want it. I used google to get examples of what other people were using and see if it worked for me.
For example in the Shooting menu, for my 'Sports' settings, the image quality is set to jpeg and ISO max at 400. For my 'Lowlight' settings, the image quality is set to raw and ISO max at 1600.
In the Custom settings menu, the 'Landscape' settings, the AF-C setting is set to Focus, but in 'Sports' it is set to Release+Focus.
An example of usage is, I was at the London Thames Festival last weekend. During the day the banks were set to the General settings, when I happened across the Taekwondo demo, I switched the banks to the Sports settings. At the Night Carnival, when it started to get too dark, I switched the banks to the Lowlight settings. It just saves a bit of time, instead of going though the menu and changing settings for different scenes.
To set it all up, I used
this as a starting point and just tweaked it to what worked for me, also have a look at this
flickr group
Of course, there is a lot more to it!