ALTANE is a Gameboy cartridge reader and writer. It can dump ROM contents, write to flash cartridges as well as back up and restore save data such as game saves or LSDj songs. It connects to your computer over USB, and works with Windows, Mac OS X and Linux. It's available now at Gameboy Life.
The ALTANE software communicates with the hardware through a USB virtual serial port, using an FTDI chip. For modern operating systems (Windows 8 and higher, Mac OS X 10.9 Mavericks or higher) the driver may be installed automatically by your operating system. Users of Linux may use the open source FTDI driver. If it isn't automatically installed, please go to the FTDI driver page and download the VCP driver corresponding to your operating system.
The software that communicates with the ALTANE hardware is written in Python, but comes as a native Windows or Mac OS X executable, so no installation (apart from possibly the FTDI driver) is necessary. Currently, the software is in the beta stage, and preorder customers will receive a link to it via e-mail.
Go here for an introduction to the software, and download links.