Solfetta is an ear training app that can also just be used as a handy web-based instrument. It is based around playing melodies with a focus on the Solfège names of the notes, unlike other ear training apps which typically use a quiz format. I think this way is more fun! Watch the demo on YouTube. Instructions and source code are on Github.
Sight Snap is a game designed to build speed in recognizing note names. It presents a set of tiles representing notes that can be matched in any order which gives a greater sense of fun and freedom versus the quiz format. Instructions and source code are on GitHub.