I started developing on Android platform in the late 2013.
The main project that condensate all my experience on this platform is Blum. Blum is a simple, clean and fast Twitter client. It's the most complete project I've ever done. It uses a lot of android stuff: IntentServices, Fragments, Animations, RecyclerViews, CardViews, a lot of common used libraries (AppCompat, Picasso...), multiple themes, Broadcast Receivers and a lot more. The app is free on Google Play, but it's also open source so you can browse the code on github.
Other projects I've developed for Android are also available on Github (at least the ones I've released). The most interesting, other than Blum, is maybe Merisi.
I've done a lot of things in Java at my university, from basic stuff to threads, from DatagramSockets to Servlets, from JSP to Hibernate.
As you may expect, the most java code I've ever written was for Android, but I have solid basics of Java to use this language in a lot of scenarios without too much problems.
Let's start saying I love Python. I've learned the basics of this language just because a script written in Python it's beautiful to read.
I've never had a chance to use it in a real project, but I use it quite often for small tasks like download the last episode of my favourite italian Radio show, use Pushbullet from the command line or automate my android app testing with Monkeyrunner.
I also like to solve some problems on Codeeval, from time to time, and in the most cases I use python.
My poor skills as a web developer are well expressed in this page.
I understand the basics of html/css/js but not much more. I've studied it a little bit at my University and used them in some cases, but always small stuff.
I've played with JS a little bit more cause it's used in QML too.
I've used C# in just one university course, and developed a project with it.
In particular, I created a Pushbullet client as an Universal Windows App, written using C# and XAML.
It's not a big project but I had a chance to play with really nice C# features, such as LINQ and Lambdas.
I've developed small apps with QML for Ubuntu and Sailfish OS, but maybe the most interesting is, in my opinion, AirBattle.
AirBattle is a cross platform little game, that can run with no problem on Windows, Linux, Mac, Android, iOS and so on.
My OS of choice is Linux. Currently, I'm running Ubuntu 14.04, but in the past I've tried other distroes too. I'm quite familiar with the terminal. I use Windows too, but I feel more comfortable in a Unix-like enviroment. I've never had a chance (the money) to play with OSX.
I've used git quite a bit, as you can see from my Github account.
I've wrote a lot of C code, but that was only university excercises. I've never used it in my projects, that's why it's here and it doesn't have a section on its own :).
I also know SQL enough to use it with SQLite in Android and QML projects, and with DB2 with JDBC at university.