The heliograph would be an alternative, if sun light is available. One of the fortified towers that exists near my town is called "La torre de l'heliògraf", the heliograph tower, because its old primary purpose as communication repeater. The tower is situated following the actual AP7 highway course, the ancient roman road "Via Augusta".
http://en.wikipedia.org/wiki/Heliograph
Another simple system available, very similar to the "Télégraphe de Chappe" described by Mohoender, is the use of a large rectangular signal panel, divided in 9 windows in a 3 x 3 pattern, each letter codified as a different configuration of the panel, depending if each window is open or closed. Sadly, I do not remember the name.
The use of these systems, with the help of binoculars, can provide a good and quick method to communicate different posts at visual range. It seems a logical development for organized areas where villages with, for example, bell towers, can provide safe spot for repeaters. Of course, isolated repeaters would be too much vulnerable, and their elimination could cause the failure of an entire network.
In game terms and under the traditional v1 or v2 setup, I think that systems as the "Télegraphe de Chappe" or the heliograph can be reasonable used between two or three important spots under the same local government.
And finally, at least here in Spain but surely in other places of Europe, a lot of small rural villages (those who have the best survival chances in Twilight world) keep the traditional bell strokes to inform the inhabitants about important things, like fires or the need of an urgent meeting. The sound of the bells can be easily heard from neighboring villages. The old "call to arms", the "somatent" bell stroke here in Catalunya, is still documented in the churches and could be easily recovered.