What are you trying to do?
Vaguely, i wish to make modular components such as individual sensors, controls, actuators, etc that can be grouped to form larger physical interfaces or devices.
Does it have to use an ATtiny?
The requirements for above example mean ATmega is maybe over sized and over spec & cost becomes an issue for a large number of them,I was thinking of ATtiny45 in 8 pin, if there is a ATmega of similar size that would do.
I literally have not programmed or tried electronics before purchasing Arduino & just about understand the Arduino examples, just to give you an idea of my ability & knowledge, hence asking the initial question.
So most of what i have in mind is just ideas right now.