With an Arduino you can create things that may seem complex in a simple manner, and one example of this is by Instructables user "electricloser" with his combination lock. By using four potentiometers and reading their value with analogue inputs, a "four position" combination lock can be made without much effort. When the pots' are in the correct spot matching the pre-stored values, a servo unlocks the door mechanism allowing the door to be opened, and when the combination is changed (a potentiometer is moved) the door locks again, for example:
If you found the project above interesting - but not sure how to start with Arduino - then the best way to learn is with our Experimenter's Kit for Arduino:
The package includes a wide variety of parts, sensors and modules including: a servo motor, lights, buttons, switches, sound, sensors, breadboard, wires and more. Furthermore a Freetronics Eleven Arduino-compatible board is included to make this an extensive hobby experimenter, inventor and starter kit. However we don't leave you alone to figure it all out, included is a great project and instruction booklet, plus access to a supporting web page and software examples. In other words - this is everything you need to get started for a fun range of electronics and Arduino related projects!
So to get started or for more information and to order, check out the product page.