[bjustin]

I have a 13" Macbook Air with a reasonable 1440x900 resolution, and I can fit about 1 1/3 windows on screen, at best: a narrower-than-usual browser window and TweetBot.

Laptop screens are generally not wide enough to fit two windows side by side. Even the ones that are, such as your 1080p 15" laptop, are unusable for most of us due to tiny text and so on.

[comex]

My 15" MBP at 1400x900x2 is wide enough to fit a split editor, or an editor and part of a terminal (I find that having part of a background window visible makes it less jarring to switch to it). I wouldn't mind it being physically taller, but I wouldn't want it to be any narrower.

[bjustin]

1440x900 is just enough for me to use Sublime Text 2 in two column mode, or Xcode with the assistant editor. I do have to hide any sidebars for both to be usable.

I stand by earlier post for, say, a web browser or email client.

[icebraining]

I can fit two windows on a 1280x800 13" screen just fine. You need applications with little chrome to make it work, though.