for a long time I was one of those people who didn't like flash introductions to websites preferring to go down the jakob nielsen route of usability when designing as well as using the internet, and I know that a few years ago the most clicked button on the internet was skip intro!
however I have changed, obviously with the brandband pretty much the norm. a good flash introduction can really help and differentiate design as far as a website. watching the way the students I teach use the internet gives me a real insight as to how people view things and I have noticed that a good short flash clip adds to the site. to this end I have started to add into some of the teaching I do flash animation especially centred around web intros. concentrating on a really tight, well thought out, well structured mini film.
one example I think works well is the intro on the kustom footwear site.