Asus Eee's forever
Regarded by many as the first truly affordable mini laptop, they still have lots of life in them, especially as they're so cheap 2nd hand, even if they're not being made anymore and superseeded by 'ultrabooks' they still continue to chug along as useful devices.
My Eee count now resides at 6; my original 701 from the first batch that entered the UK which is still going strong along with another 701 which doesn't have a working touchpad but otherwise is fine, two 'dead' 900s that have failed onboard 4gb SSD's and missing screens (I broke 2 sceens by mistake so had to salvage), a fully working 900 (still very useful), and a 901 with a cracked screen I was given which has been upgraded to two SATA 2.5" drives with SATA connections (60mb/s read/write) to become a basic VNC controlled HTPC with a Microvison SHOWWX+ pico projector pointed at a 6 foot wide screen.
I do have a 7" Nook Tablet which is a nice toy for media consumption but is not always substitute for a 'proper' computer - even an Eee, I dislike the fact that current computing technology is moving away from multitasking to singletasking by having programs (apps :P) running in fullscreen.