OpenStreetMaps (OSM) is a jewel of the open-source data explosion of recent years. OSM is unique as data products go because it is crowdsourced– with the goal of creating a completely free editable map of the entire planet. Indeed, OSM wasn’t even possible until the advent of cheap, widely available GPS and the ubiquitous internet. Since its inception in the United Kingdom in 2004, OSM now has over a million registered users, not all of whom actually contribute to the database. OSM considers the data the end-product and not the map.
Data is widely available for many countries, though data quality can vary. However, data quality is comparable to that of commercial data– and in areas where no other data is available but OSM data, what is available today is a lot better than nothing. Data available include streets, but also some utilities, hydrography, buildings, and other features as well.
… but it can be difficult to just get what you need if you try to download OSM data… the datasets are HUGE (the planet file– self explanatory– is about 30GB).
Instead, a number of websites offer country and area extracts of the OSM planet dataset, updated on a weekly or daily (sometimes even hourly!) basis.