GoogleMaps is great for looking up the location of places, but if you want to know the longitude and latitude of the place you are looking for, there is no obvious way to gather that info.

However, there is a way.  When viewing the location you want co-ordinates for, makes sure it is in the dead center of the GoogleMap you are viewing and then place the following code in the address bar of your web browser:

javascript:void(prompt('',gApplication.getMap().getCenter()));

After you hit enter a box will pop up with the co-ordinates you want.