I hope that you are doing well. :) Recently I was asked to write more about what I am working on -- in English and with pictures. I will try. English is not my mother tongue, so please forgive me possible grammar errors.
My primary interest in OSM is routing and, more exactly, using osm-data in CityGuide. CityGuide is popular navigation software in Russia.
It is available for many platforms, including Android, iOs, Win Mobile and Win CE and some others. Here is CityGuide’s page on Google Play Market
CityGuide is capable of many features: traffic aware routing (with live traffic updates), address search, 3D view with 3D Buildings, voice guidance and some others.
Colored lines with numbers are estimates traffic speed, kmph
It is said that seeing once is better than hearing twice, so here is also a brief video demonstration (unfortunately with Russian UI, English UI is also supported, but no video has been recorded yet :) )
Osm-data based maps for CitiGuide are currently available for Russia, CIS, and some other countries of the World.
Also we have some kind of quality assurance tool - http://peirce.gis-lab.ru/qa It includes several different tests - including road network connectivity and integrity of address search.