Multiple monitors

With PCs more commonly having multiple (normally 2) monitors, it amazes me that so many programs can't handle this.

Two common problems.

1. Screens that center on the desktop, not the screen.
2. Programs that open additional (often modal) forms in the other screen.

Screens that center on the desktop, not the screen.
With the desktop being spread over two screens any form that is centered on the desktop will be half on one screen and half on the other. This does not look good and forces the user to reposition the form before they can use it. Forcing the user to do unnecessary tasks before they can use a program is definitely not good.

Programs that open additional (often modal) forms in the other screen.
It is incredibly awkward and distracting to have to keep looking between screens to see where the new form has gone. This is especially awkward when opening a small dialog, such as a search/find dialog. A modal dialog opening in the other screen can be incredibly confusing, until you realise what has happened, and should be unacceptable.