The GTK+ Remote Desktop Client
Here are some screenshot of Remmina 1.1.1 running on various desktop and distributions.
Remmina Main Window on Ubuntu 14.04
The Indicator Menu on Ubuntu 14.04
Remmina on Arch Linux and RaspberryPI
Remmina on Arch Linux
Remmina Main Window on Fedora 20 (German)
Remmina Main Window on Fedora 20 (Japanese)
A RDP Connection
Another example of RDP Connection