I quite often open a bunch of windows in one Space and minimize them, yet have the application open in another Space. This turns into a pain when I go to un-minimize the windows, as they then open in the Space in which they were minimized.
However, if you Command-click a minimized window in the Dock, it opens in the current Space, instead of its originating Space.
[robg adds: Based on my testing, this only seems to work in 10.6, so I've marked it as such.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090925170821425