OpenCage Geocoder

OpenCage (from Lokku Limited) is a new and promising contender if you’re looking for an easy way to geocode (both forward (i.e. address to lat/long) and reverse (i.e. lat/long to address)).

Cost

According to their FAQ, OpenCage will be free while in beta:

During the beta period, use of the OpenCage Geocoder is free of charge; the pricing page will always have the latest information.

Libraries

Multiple client libraries (e.g. in Python, Ruby, PHP, Javascript) make calling OpenCage very simple.

Results

OpenCage returns results in either JSON, GeoJSON, XML, a map, or google-v3-json format.

Give it a try using their quick start. A free key is all you need to run their examples.