This really isn't an instructable, as it is a helpful hint.
When I create new creations on my breadboard, I got tired of searching for the battery connectors, and sometimes I forget to order them, and I have to wait until they arrive. So, I just simply took a prototype board and permanently mounted my three most commonly used battery packs: 3V button, 3-AAA, and a 9V. I connect these to a set of male pins and then use a male-female connector to connect it to the breadboard.
Then, whenever I need to power my board up, I have it all ready to go.