I'm designing a user interface for a large touchscreen device running Linux. What would be the best toolkit/developer kit/SDK to use? The only requirement is that its able to run on a semi-low performace device, and that there is a Linux version.
Nice-to-haves would be build in support for effects/animations and a modern look-and-feel, but they are not necessary.
I'm looking at Adobe Flex/AIR already, but I'm not sure if the device will meet the minimum specs.
Try QTopia (http://trolltech.com/products/qtopia) It's from the same stable as the popular Qt desktop toolkit.
I agree with Mopoke, QTopia is what you want.
It has support from some graphics hardware (2d and 3d), and can also use the kernel framebuffer device if that's all you need.
It's based on Qt, a very well-designed object-oriented GUI framework
It's available for both open-source and commercial projects, although closed-source projects need to pay a license fee.
You should check out whatever tool-kits are used for the Chumby. It's a completely open-source Linux device (open schematic, open source software, etc) with a very rich user-interface (color touch-screen, builtin wifi, USB ports, etc). I believe it's user-submitted "applications" are Adobe Flex/Flash based but there are a variety of open "hacks" including a port of Quake that can be easily downloaded and run.
A bit late to this question, but I'll add in that Storyboard Suite from Crank Software might also be worth looking at.
It is specifically designed to meet the needs of user interfaces for embedded products and was designed from the ground up with that in mind. In addition to supporting multiple operating systems and rendering technologies, it also comes with a user interface builder that allows you to quickly build up a design and simulate it on a desktop system if you don't have access to the embedded target hardware.
Thomas