They are also used as switches in some circuits. They normally have a wide selection of electrical components of all types. Their stuff is generally more expensive than at Radio Shack. The Georgia Tech Bookstore and Engineer's Bookstore carry components that are required for the various Electrical Engineering labs at Tech, like EE3741. They have a lot of the logic chips and op-amp chips.
Toy stores sell power supplies and motors sometimes.
Hobby stores usually have power supplies and a really good selection of rechargable batteries, chargers, and power supplies. One of the cheapest sources of common electronic components are non-functional electronic devices that you can strip the parts from. Such devices include tape players, radios, etc. You might be surprised how many switches, resistors, potentiometers, and transistors you can get from a broken cassette player. You really can't get integrated circuit chips, since there is really no good way to figure out what they do.