Gerade (wieder) auf Leaflet gestossen:
It is built from the ground up to work efficiently and smoothly on both platforms, utilizing cutting-edge technologies included in HTML5. Its top priorities are usability, performance, small size, A-grade browser support, flexibility and easy to use API. The OOP-based code of the library is designed to be modular, extensible and very easy to understand. Find out more on the features page.
Nachdem Google angekündigt hat Geld für Google Maps zu nehmen werden die Alternativen ja deutlich interessanter.