Ok, deserve to be strangled.
Here's some stuff I've learnt that might help someone by way of recompense.
Magazine style: want to have a thumbnail on the front that leads to a full image on the post page?
When writing the post, insert a thumbnail. Add some text to appear with the thumbnail. Then insert the <!--more--> tag to break the page. This means that on the index page you get a fast loading thumbnail with appropriate text beside the image.
Still writing the post, insert a full image below the more tag. This means that anyone clicking through to the full post will now see a thumbnail, some text, and a full image. In the stylesheet, use display:none for the thumbnail image e.g. something along the lines of div.single-post p img.size-thumbnail {display:none;}
(Thumbnail images are given a class of size-thumbnail)
And since I've been an idiot, here's some more stuff. This is when creating a series of mini-posts, magazine style - but supposing you have it set up for 3 posts in a row across the page, and don't have a special deal on that day, or anything new to post? Supposing you only have one post that day? Rather than having a blank space where the other two posts would be, have some standard posts saying something along the lines of, 'More stock in soon' or whatever.
Before the loop
<?php query_posts('order=DESC&showposts=3&cat=7,8'); ?>
The loop
<?php if ( in_category(7) ) {?>
<div class="index-box" id="post-<?php the_ID(); ?>">
<?php ;}
else {?>
<div class="more-soon" id="blah-<?php the_ID(); ?>">
<?php ;} ?>
content
</div>
What this does.
If there are posts in category 7 (your goods for sale category) then display those posts - otherwise display a different div from category 8 with a background image that reads, 'More goods in stock soon.'
Create several posts in category 8, and backdate them so that they're the oldest posts by a long margin. That way they'll always be shown last.
Not rocket science, but one of those useful little snippets it's sometimes good to know :-)