What is the single most important element of your website?

Your website looks nice at first impression. Very important. A warm (female) feeling and not to complex.

However some extra tips:
1. always leave all your menu options above (dont leave out the current one)
   (this is the best way for navigation)
2. I would make seperate "picture books" in stead of one for your portrat gallery.
    seniors
    children
    infants etc.

I don't like it to have to see a whole slideshow if I want to see the part at the end.
For example if I would like to see infants I have to struggle to page 19. I would prefer to go directly to page 19.

By the way - Your picturebook however has Java / Flash-applets in it. So even you are using it.
For me I am also using embedded flash galleries. But they look like a normal gallery or slideshow.

To finish -  If I compare your website to Travis, then my first impression with you is excellent!

I voted ease of use because if the visitor can't find what they're looking for quickly and easily, then it really doesn't matter how nice your site is as they're pushing the back button.

Really great question though.

Special Effects - I think the "special effects" is probably the least important of what you have listed.  Although I think it depends on the reason for it.  Some Flash examples would be good for this discussion, and I'm sure most of y'all have probably seen some that fit what I'm about to describe.  Some Flash sites have it set so as you go image to image in a gallery the boxes change size, colors change, the images fade, and it takes 30 seconds to go from one picture to the next.  I would consider that a special effect for the sake of the effect and not for the improvement of your site.  It's more of a gallery for the Flash designer than you.

Quick Loading - If your site takes too long to load, people leave.  No way around it.  I've heard anywhere from half a second to about 5 seconds as the most time you have to make an impression with your site.  Not necessarily fully loaded, but you need to have something there other than a "Loading 10%.... 20%.... 30%....".

Searchability - Search engine traffic is free so it's not something to risk losing.  Not working on your site with the intent of search engine techniques is like a brick & mortar store opening without a sign or a front door.  Well, maybe not without a front door but at least without a window display.

Along similar lines I have a search engine built in to my site.  Last I read something like 20% of people will go to a search box on a page before looking at the links.  So I get quite a few people typing in "prices" instead of clicking on the "Prices" link.  Now, I don't get a whole lot of searches - 2 in the past 7 days - but there are a few.

Attractiveness - I left this one for last on purpose...

I would suggest that rather than attractiveness, it gets expanded to uniqueness.  Something has to make your site stand out in the eyes of your visitors over the hundreds of other photographers.  We like to think it's our images, but often it's the site. 

Hello Bob,
I did have a quick look at your website. There is indeed a great variety of pictures.
There is something you can do better. That is your navigation. Once you enter a category the other ones are not visible anymore. This is not good. You have to go step by step back to your homepage. It is better to have a navigationbar or pulldown menu (like on my website). Then you can go to any other page you want directly.