I used PHP5, XML, HTML, CSS, JavaScript, MySQL for server side logic and users' interface and C# for mobile devices.
I also worked as DB and system administrator (FreeBSD, Apache).
In addition I supervised design and programming of software for mobile devices.
An idea was to create a system for taxi companies so as they could easily get and assign orders, know location of cars, get statistics and to use cheap (not specialised) mobile devices. Any device with GPS and GPRS could be used for this system.
The system was in beta version and was even tested in one taxi coompany, but due to world economic crisis owner couldn't find money and GoodTracker died.
Here are screenshots of beta version (click for full size):
