What went wrong with my SEO?

[Andy Johnson]

I have a site hosted on hostgator which i set up about a month ago.

Its a single word domain which is a clear mispelling of another word.

When i first set up the cart on the site, google returned it right at the top of its listings when i put in that quite unusual word. That was before doing any SEO.

Now though, its dropped to the bottom of page 2. This is AFTER doing a little bit of basic SEO through host gator.

Worth noting that the top 3 of my competitors are:
1) a photo on a myopera photosite that someone submitted in 2007
2) a youtube playlist containing a video from 2010 thats had 500,000 views
3) a tumblr page written in text speak with nothing valuable on there at all.

So the top 3 have no need for specific SEO on that particular keyword, even the 500,000 hit youtube vid would have had very few if any hits directly from searching this obscure word because its not relevant to the video, just happens to be in the title.

So i guess the question is a) what went wrong? and b) what is it that affects the search results of a single word? We've all obv had the word picked up by the google spiders so why is mine so far down? Is it just a matter of being a generally popular site to push me up?

Thanks
Also just realised, I have the .co.uk and the .net for this site, the .co.uk is the primary site with .net diverting to it. When it was first set up, the google results for .net and .co.uk appeared almost "nested". Now, the .net (divert) is the one thats actually showing up at bottom of 2nd page, with the .co.uk nowhere to be seen even as far as page 19 (cant be arsed going further than that to find it as there are 150,000 results)
Thanks Jake, global monthly count for the word is only 320 so very low competition