I've always been a fan of ultra lightweight laptops. This started back in the early 1990s when I bought an HP Omnibook 300. This puppy weighed 3 pounds and ran the new Windows 3.1 and Microsoft Office. It ran a 386SX in real mode, i.e. it didn't use a page file. Windows ran on top of a hacked version of MS-DOS 5 with an early copy of DriveSpace (from MS-DOS 6) which doubled the usable space of the 40 MB (yes, that's not a typo) hard drive. The good news was that none of that 40 MB was used for operating system or application. The operating system and Office were on a 10 MB execute-in-place flash card.
It used a 640x480 monochrome screen and had an open PCMCIA slot for a modem or NIC. It was "instant on" in that it worked much like Windows 2000/XP's hibernate/resume except it didn't dump to the hard drive. Click, it's on. Click, it's off. It had a cute little mouse that popped out on a stick from the side. The battery life was 5+ hours. I could run mine 2 days before charging.
HP's retrospective on it is here.
I went on to IBM ThinkPads including a 560, a 240, a 600, and most recently my beloved X20. My recent company issued laptop from Texas doesn't hold a candle to the ThinkPads. At home, I'm pure ThinkPads with an inventory of 2 760s, 3 600s, and a T20.