This doesn't exactly answer your question, but you could take the contrarian approach and spend time learning Cappuccino, which abstracts a lot of the archaic and difficult web UI principles away.

Web UI is difficult to define (there is no standard, but there are a bunch of competing standards) - and from a RAD perspective it's behind where the desktop was 10 years ago.

You may also get some benefit from looking into web frameworks such as Catalyst (if you know Perl), or Django or Rails (for Python and Ruby respectively). Examples for those frameworks really are very good walkthrus of creating a webapp.