The other major plus of Cartagen is the fact that it can be hooked into by css to infinitely "re-skin" the mapping data making it look however you wish. This is great from the perspective of designers and other visual workers.

Another key advantage, as pointed out by Digital Urban, is that "The ability to build applications that run naively in the browser without the need for plugins will allow agencies such as the police, government, health service etc a to view data that is currently restricted due to rules on installing plugins/software on networks".

Check it out at Cartagen.org.