Someone asked if it's enough to put a H1 tag around the title of his Arthemia site to make the template more SEO friendly.
My opinion I want to give you here:
looking at your (or any other) site with styles disabled or 'view - no styles' you can see how a theme values any links.
In Arthemia I am always missing the h2 tag for post titles, there is the h3 for categories the most important...
So to put h2 around the titles of posts in index.php and archive.php would be a suggestion of me.
In single.php I use h1 for this post title, because it's the only one on that 'page'.
Finally on your site is not much content text compared to all the links.
Let's say I click http://availablelightonline.com/blog/2009/04/27/rest-in-peace-pontiac/, I find four words of content only (You will be missed), but this post has more than 20 tags, all going to exactly only this one post with only four words.
Do not use more tags for a post than there is content, tags are your keywords! This Rest In Peace Pontiac has actually no content but a page full of links.
I would use one category per post and one to five tags per post only and put the other important words in real text making sense into the post