When you hit the V key the speed clock icon appears in the right top corner of the screen. It can't be clicked.
In GOG.com version of the game the cheat code is WINTER, exclamation icon appears in the same place as the speed clock icon when cheats are enabled. Speed changes with the told Alt + 1 ... Alt + 6 key combinations where 6 is fastest.
Cheats also make it possible to construct another headquarters. In campaign game it acts almost like a warehouse, you don't get any more stuff in there, but in unlimited game it is like a real new headquarters with the same amount of stuff you had when the game started. To create a headquarters you can simply click outside your borders.
Also, as far as I can remember, harbor building is also enabled by the cheat. You just can't see the effects because most maps don't have any coastal castle spots where you could built a harbor and the map editor that comes with the game is unable to generate these. Last but not least, harbor only works in campaign games, so you have to replace DATA\MAPS\MISS_XXX.WLD with your own map. To generate coastal castles you can use the map generator, just open a map you've made and hit Tools > Coastal castle fix and save the map.
Post edited September 18, 2009 by Merri