Firstly, your site is still relatively young, your domain name was registered in July 2006 and expires July 2007. There is a belief that Google ranks websites that have a longer domain registration period i.e. it would be better if your domain name expired in July 2011 (five years), this gives your domain name more credibility as Google knows you aren't going anywhere (I mention Google because they have the monopoly amongst the search engines).
Secondly, you will need to continuously create more backlinks to your site (high priority of Google's algorithm). Advertising in directories is good for backlinks but they don't provide the traffic that they promise. As your site is still young I suggest keep being active in community forums like Yahoo Q&A and inserting links to your site wherever possible. Try networking at myspace (biggest online social network in the world), also forums that are related to your website etc... Basically get inside your target market's head... where will they be online? I think history students would be a good place to start?
You can't rely on search engines to provide organic traffic until your site is more mature. Don't panic though, it will come. However you will need SEO at sometime or other to get top rankings. I do provide my clients with free SEO reports as I was once where you were and know how you feel. Don't worry it's not a scam, I make my money through web design. Once you've read through the SEO reports you will know what needs to be done.
There is too much to mention in this forum, I have started a blog where I have some helpful links for marketing. It's still new though, I only began yesterday so please bare with me...
One more thing... Your site took quite awhile to upload, even with my broadband... I suggest decreasing your jpeg size or converting them to .gif format. This will make a world of a difference and will keep visitors clicking through your site without becoming frustrated.