If you're a frequent user of Spaces, you'll often find yourself moving windows between spaces, however, if you like to have your large windows properly centered (e.g. in Safari or other browsers) you'll find it difficult to properly center the window when moving between spaces, leaving part of the window off-screen, and needing to be adjusted.
The solution is simple, all you have to do is enter Exposé from the spaces overview, and then move the windows between spaces. Once you exit Exposé, you'll find the window will be in the exact same location on the screen it was in the previous space.
[crarko adds: I tested this, and it works as described. On my MacBook I just used the default keyboard settings of F8 to get into the Spaces overview, and then F9 to bring up Exposé in 'All windows' mode. If you've changed those key bindings, use your correct ones, or you could combine the two using this hint.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20100831120738879