Thanks for the helpful insight, Stevie. But if 10,000 Russian sites started linking to me, wouldn’t google have to assume that I’ve paid for that? I mean - What does google use as a proof of someone doing black hat SEO, like paying for thousands of backlinks? Thanks so much for your time.
[FONT=Verdana]If it thinks the links pointing to your site are dodgy, Google will just ignore them when working out your ranking. They won’t help you or hurt you. On the other hand, it is likely that the site that is giving the dodgy links to your site will be penalised.
But that isn’t the case here. The chances are that there aren’t any links on these dodgy sites to your site. They’ve sent a robot round your site with a forged “referrer” header, but there aren’t any actual links there. Google won’t know what’s showing up on your logs, so it won’t know anything about this.[/FONT]
There are many possible reason of drop in ranking but possible reason this time is Google Latest Penguin Update which is very strict to quality. Your website need to have complete unique content which is not to be copy from anywhere or copy on anywhere secondly your website must need to have backlinks that is coming from same theme website and not at all from FFA Pages. So rectify between these issue and send reconsideration request to google.
I had the same problem with my website. It went down in SERP multiple pages for multiple keywords. Then in 6 month stime all the keywords came to higher positions than before ( stayed there for almost 1 month) and now it has gone down again for what ever keywords the problem had. I think it will take another 6 months to be back and god knows it will repeat this procedure again?
There’s no rest for the wicked, as they say. 
You just have to keep working at SEO. The search engines are laws unto themselves, changing their ranking criteria regularly (which seems fair enough to me). If you want to rely on them to get noticed, you have to keep vigilant and not rest on your laurels. It’s just how 'tis.
This is really a good topic for me as i am in same situation. My site was ranking in 2nd pages since 2 years and after the penguin update it is shifted to page 3. I have unique content at my website and didn’t receive any email through webmaster as well. Not able to find the way to get my ranking back as it was.
Saudi-TOEFL,
I think that you need to update your blog regularly. You seem to rare update content at your blog.
Both content and backlink are important factors for SEO at Google.
Keep building backlinks and remain active in communities such as this one. I noticed that you don’t have a link to your website in your signature. You should. Join other webmaster forums as well and post a few things every day. You should also leave comments on blogs with your signature.
You cannot have a signature on the SitePoint Forums until you have been a member for 90 days, and the OP only joined in April. Even when he qualifies for a signature, it will not help with backlinks, because signature links on this forum are nofollow. The same holds true for many other forums and blogs.
I think this guy talking about keywords, same situation with mine… without doing anything google dropped my primary keywords from seraching page, from top 3- 30.
some dropped to 50+…
I don’t know why but since then, I refreshed my content, created some new pages to website and made some back links slowly gradually , after 2 months, it reranked on top 10.
just my experiences, for your reference only.