I use Ubuntu on a daily basis and want to try Suse on my second laptop.
Neither Startup Disk Creator (both versions on the Ubuntu Universe) nor unetbootin allow me to use anything different than another Ubuntu distro to create the live USB key.
I don't use windows anymore, so doing this on a pc is not an option.
Is there any other way / application?
If the .iso is a "hybrid mode" image (like most Ubuntu and Debian images these days, have no idea about SUSE), then you can just write it directly to the USB just as if it was a CD-ROM drive. For instance, using dd.
If the .iso is not a hybrid mode image, then you can use UNetBootin, available from Ubuntu's repositories, which is an easy way to burn an ISO (for a Linux distro) to a USB key.
UNetBootin does not restrict you to using it with Ubuntu only - it will allow you to use an .iso you have previously downloaded, and that .iso can be of any distro.
Download live ISO for gnome or kde from here.
You can use MultiSystem(tutorial and download link here)just an alternative, but you can also use unetbootin for SUSE.