My iPad. Really. Since getting it (original model - WiFi 16 GB, in January,) I have used it more as my 'main computing device' than any other computer in the house.
Other than that, it would be my 'Hackintosh' (see signature - which is presently on the fritz,) and my first-generation MacBook (black, 2.0 GHz Core Duo, 2 GB RAM, which is acting as my desktop until I get around to fixing my Hackintosh.)
Other than that, it would be my 'Hackintosh' (see signature - which is presently on the fritz,) and my first-generation MacBook (black, 2.0 GHz Core Duo, 2 GB RAM, which is acting as my desktop until I get around to fixing my Hackintosh.)