It does look very dated.
Given that there are already graphic demos written, why not use them to give some pizzaz? When you start up the Viewtop, it could run the "pointilize" effect to dramatically bring a splash screen into view. Further, you could take a cue from Google Nexus One and animate the background in a subtle way while people are browsing the icons.
Why not make clicking the applications reuse the window instead of popping up a new one each time? That would mitigate performance concerns from any wallpaper animation, and also avoid the web "pop up" taboo...
I feel like one of the key points to drive home—that this is being fetched dynamically from the network—is buried. If the esoteric unset-defaulting was axed and instead users were told to type:
That would be better. (Also, why is it that my Rebol 220.127.116.11.5 on OS/X is not starting in security "ask" mode? Even after +s it's allowing writes to files...)
As for viewing the code, that should be more exposed within the apps themselves. And it needs to be commented to be useful to new users. Perhaps the editor you click could count the number of comment and non-comment lines separately, and let you view with or without them)
I'll suggest of course having this discussion at Talk:The_Rebol_Viewtop on the wiki.