Version:            (using KDE KDE 3.4.2KDE 1.2)
Installed from:    Fedora RPMsFedora RPMs
OS:                Linux

You should be able to select multiple windows (maybe in something like Bug 66471?) and then Tile them, like you used to be able to do in Windows (though it didn't let you select them; it just tiled whichever ones weren't minimized).

The thing Windows didn't do right, though, is that, instead of each little tiled window having their own resizable borders, the border that is shared between two windows should behave more like a "split" view in a single app.  

Say you select two windows and you tile them horizontally; one is on the left half of the screen and one is on the right half.  

|--------------|--------------|
|              |              |
|              |              |
|              |              |
|              |              |
|              |              |
|--------------|--------------|

Now the border in the middle becomes a split line instead of two independent resize borders touching each other.  If you move the split line to the left, the left window shrinks while the right window grows, so they are always using up the entire screen. 

|---------|-------------------|
|         |                   |
|         |                   |
|         |                   |
|         |                   |
|         |                   |
|---------|-------------------|

Or maybe you could keep the regular resize borders, but add the split line between them, allowing differentiation by the cursor changing when you hover over each.  So as you move the cursor from left to right, it starts as a regular arrow, changes to a resize cursor for the left window, then a split cursor for both windows, then a resize cursor for the right window, and then back to a regular arrow inside the right window.

Closeup of joint border between two windows (a few pixels wide):

    Inside | Resize     | Resize  | Resize    | Inside
    left   | right-hand | both    | left-hand | right
    window | border of  | windows | border of | window
           | L window   | at once | R window  |