Qt is my main choice of development platform, and I have spent most of my professional life coding Qt based applications. I started coding Qt on Linux all the way back in 1997 when Qt was at version 0.3 or something around that. Occasionally, I have been in longer contracts that didn't involve Qt, but most of the time, since i graduated with my Masters Degree in 2000, have been with Qt as the main focus. Several years have been spent doing nothing but Qt coding.
I am of course a Nokia Certified Qt Specialist. And I keep hoping they will create a much tougher certification level for us true Qt experts.
There are very few classes in Qt I haven't been in touch with. I know all of the central parts of Qt inside out. I have a lot of experience with all of these Qt modules:
Most of the Qt software I have built have been desktop software, but there have of course also been a lot of code for embedded applications.
My main development platforms are Windows and Linux using Qt Creator, Visual Studio or GCC. I have some experience with other platforms or systems.
I use QMake or CMake for the build system. If a Windows installer is to be built, I normally use NSIS.
Other tools I am using daily include: Versioning software (Subversion, git, bazaar, ClearCase, CVS or similar), make, cppunit (JUnit for C++), valgrind, gdb, Python, Web applications, PHP, Apache and many many others.
In my opinion, by far the most important skill when working with Qt is to thoroughly understand it. In any project I am involved in, I will create a lot of code. But even more important is that this code is done with a proper sense of Qt architecture, and is built to last. My code style is to create code that is flexible enough to work for years without modification.