as you well know, exposure, exposure, exposure is the most critical part of your web site success.  visual appearance, content and functionality are secondary. your viewers must find you first before they can appreciate your design, data and delivery.  the problems are twofold:

sounds confusing?  just imagine you are teaching a class of international students who do not speak a word of english, and each student has their own unique web site which represents an "apple," and they all want their "apple" on your desk (computer screen).  not only do they each use a different word for "apple" (keyword), they each have different cultural verbal protocols to convince you to see, accept and consume their "apple" (method).

on the outside, doorway pages can reside on any web site, and redirect users to your web site via clickable hyperlinks.  i do not use meta refresh tags or various redirect "scripts" which are not acceptable and looked upon very negatively by some search engines.

on the inside doorway pages reflect different page titles, meta tag keywords and keyword-phrases, meta descriptions, image descriptions, themes and text body content.  this information is geared to index a page with the different search engine methods, as well as covering a huge amount of various keyword &/or phrase queries.  

i also go one step further ... by establishing different themes on keyword searches!  for example if you are selling real estate, the obvious keywords are:  house for sale, properties, real estate, realtor, etc..

but what about the people who are not looking directly for real estate?  sounds like a contradiction? not really, in commerce, impulse buying covers 35% of your sales.  the point is to put a bug in potential customers head that will peak their interest and perhaps eventually close them on a sale.

so, let's say you use a recreation theme with keywords such as:  recreation, cabin by the lake, fishing, outdoors, weekend get away, etc..  now, based on this information, your site could very well attract someone looking to buy a piece of recreational property. you can have web page themes on "commercial real estate," "mortgages" and "relocating or moving?."  

i take the point of view and angle of attack with search engine promotion - that:

all roads lead to rome, and your web site is rome!