What .gitignore I should use with QT projects? (QT Creator)
You might be interested in this little project: https://github.com/github/gitignore
There you can find .gitignore files for several programming languages, OSs and even more.
The .pro.user file should go into .gitignore. It is not meant to be shared between developers and/or platforms.
I would further add any file that is generated by the build step: This does of course include the Makefiles.
Some additional things you might want to throw in are ".DS_Store" (created by Finder in Mac OS X -- it does pretty much the same thing as "Thumbs.db" on Windows) and "*.bak" (a common extension for temporary backup files, predominantly found among editors on Linux). You may also be interested in this article on cvs ignore which provides a fairly large list of common file patterns to ignore.