switching between inline and external

[Gregory Seidman <gss+mutt@xxxxxxxxxxxx>]

I receive HTML mail from time to time. We all do. Some of it is even stuff
I want to read, and usually I want to read it inline. Occasionally I want
to put it in a web browser (links, lynx, w3m, whatever) and treat it as a
live web page. Is there an easy way to switch between behaviors from within
mutt?

Also, I obviously need two entries for text/html in my .mailcap. What
should they look like? Currently I have only an inline version:

text/html; w3m -T text/html -dump %s -ppc 9; copiousoutput

--Greg