Homepage says "TwoUp Has Been Discontinued" they suggest using Cinch or SizeUp.

Damn, 400 char limit on posts. Reconstructing the script from the two parts left as an exercise to the reader.

tell application frontApp
if (frontApp = "Macintosh HD:System:Library:CoreServices:Finder.app:") or (frontApp = "Macintosh HD:Applications:Mathematica.app:") then
set bounds of front window to {disp_x1, disp_y1 + 44, disp_x2, disp_y2}
else
set bounds of front window to {disp_x1, disp_y1 + 22, disp_x2, disp_y2}
end if
activate
end tell

set frontApp to (path to «constant afdregfp» as Unicode text)

tell application "Finder"
set {disp_x1, disp_y1, disp_x2, disp_y2} to {0, 0, 1920, 1200}
(* Assuming that we have only one desktop we can set it to "bounds of window of desktop"*)
end tell

The same functionality can be achieved in Applescript, which is handy if you want to trigger it from launchbar/quicksilver/gsb/etc. I pasted below the source for expanding windows to fullscreen on a 1920×1200 resolution monitor. Tweaking the code a little will give you half-screen and quarter-screen resizing for arbitrary monitor size.

god this is an amazing idea. Thankyou!

developer is building a version with quadrants and fullscreen. In the meanwhile i'm searching for an alternative..

This should've been a staple of the OS since like 10.2

But since it's NOT a part of OS X, this app makes things very, very convenient.

Thanks, this is very useful!

This is JUST what the doctor ordered. Perfect.