These days HTML is the most reasonable approach to anything involving 
    fonts and images and interaction. It's not as beautifully direct as REBOL, 
    and being trapped in a browser is somewhere between limiting and annoying, 
    but the visual toolkit is there, and it's ubiquitous. (For the record, I 
    would have solved the "list all the filenames..." problem by generating 
    HTML, but firing up a browser to display the result is a heavy-handed 
    solution.) 

I know it's Microsoft-only, but I think XAML is an attempt to solve exactly this problem. It's a declarative UI description language, but without some of the legacy baggage of HTML.