Building various types of robots is a fun and interesting challenge, and if you've moved past the basic Arduino-motor control style then consider making something much more controllable such as a hexapod - a crab-like robot with six legs controlled by twelve servos. Such a design has been published by Instructables user "orangenarwhals". Although it may seem complex, with the broken-down sequence of instructions you'll have a hexapod in a day or two, an example of which is shown below:
If you'd like to learn about Arduino, servos and more - but not sure how to start - 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.