Another advantage of web apps is that they are automatically platform independent - so long as the page designers permit it to be by keeping it simple. Avoid jazzy dhtml, flash, clientside scripting, etc., etc.
Yeah, in theory. In practise, many sites aren't simple (and
considering the original post, this site isn't going to be
simple either), and aren't platform independent at all.
If you can afford to be 'simple', Java programs can be platform independent as well. And so a (Perl|Python|Tcl|...)/Tk application.