A count-down timer developed with Qt 5.3.
Windows screenshot:
Mac screenshot:
Binary:
In "releases", you can find statically linked binaries that can run by double-click, without "installing". Since they are statically linked, the size is a bit large: 7MB after being comparessed with zip, and the original binary size is more than 14MB. They have been tested on Windows 7 64bit and Mac OS Mavericks 64bit.