Recent years have witnessed progress of public institutions in making their datasets available online, free of charge, for re-use. This notwithstanding, there is still a long way to go to put the power of data in the hands of citizens. This article suggests that transparency in the context of open government can be increased through web maps featuring: i) Application Programming Interfaces (APIs) which support app and data usage tracking; and (ii) 'transparency badges' which inform the users about the presence/absence of extra, useful contextual information. Eight examples of web maps are introduced as proof of concept for the idea. Designing and implementing these web maps has reminded of the need of interactive guidelines to help non-experts select vocabularies, and datasets to link to. The ideas presented are relevant to making existing open data more user friendly (and ultimately more usable).