Although it's easy to get carried away with using microcontrollers for various tasks, there still lies many tasks for using digital electronics and thus logic ICs. Doing so is educational due to the study of logic gates and their theories, or you may be repairing some older equipment. Either way, the project by Instructables user Zoran1389 will be of interest.
They have demonstrated an Arduino-based logic IC tester that can be used to check TTL ICs by applying the full truth table to the particular IC and displaying the result. In doing so you can test old ICs, and also get a deeper understanding of logic gates. In conjunction with the ICs's data sheet you could modify the sketch for almost any IC and run through all the possible outcomes.
It's an interesting project that bridges two eras, so to get started visit the project Instructable. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're interested in experimenting with Arduino for your own inventions - but not sure how to learn - order one of 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.