OpenStreetMap is a free (as in speech) map created by a community of mappers. Anyone can join and anyone can contribute. Unlike most other maps, you are allowed to use the maps for anything you want, even commercial purposes. You can even download all the data (coordinates, ways, polygons) used to create the maps and use them to create other maps, routing software, or whatever you can think of. As a result of this freedom, people are more likely to contribute and we can see this from the various maps of Magalang - OpenStreetMap seems to be the most complete one out there.
OpenStreetMap can be edited to incredible detail, and there are satellite images as background to help tracing. If you're looking at the map and notice something missing, just click Edit and improve it. I recommend this beginner's guide for people interested in contributing to making an even better map of Magalang: http://wiki.openstreetmap.org/wiki/Beginners'_guide
Because of the open nature of OpenStreetMap, people have created lots of different types of map using the same data, such as the Cycle Map:
And MapQuest's map layer:
MapQuest is one of many websites that use OpenStreetMap's map data, just presenting it in a different way.
Practically everyone knows about Google Maps, and they are generally very good, but in the case of Magalang, they're not as complete as OpenStreetMap. You can also edit Google Maps through Google MapMaker, but their maps are only free as in beer, which means that even if you help them improve their maps - basically give them data for free, you can only see their generated map tiles (the images of the map), just like everyone else can, but you can't use them commercially, nor can you see or use the data behind the map.
One great thing with Google Maps is the satellite images. Unfortunately, again, you can only look at them for free. You can't use them in your own material.
Bing Maps is Microsoft's map product. I'm sure Bing Maps is good in some other areas of the world, but their map of Magalang is practically useless. I'll let it speak for itself:
There is a good part though - the aerial photos:
And unlike Google, surprisingly, they actually allow OpenStreetMap mappers to use them to trace roads, buildings, rivers and other features. Hence, Bing's aerial map is OpenStreetMap's default image layer when you edit the map, replacing the older and (mostly) less detailed Yahoo maps they used earlier. Obviously, Microsoft don't allow you to edit their map - that's not their style, and this is likely the reason their map is so poor. But it is very kind of them to allow the aerial maps to be used by the open mapping community!
If you know of other online maps of Magalang, please let us know in a comment below.