Here's a good explanation of the problems that can arise from having links to "http://www.seo-search-engine-ranking.com/" and "http://seo-search-engine-ranking.com/".
The problem arises because search engines think they're looking at different URLs and therefore different sites. Most webmasters can use a .htaccess file to solve the problem. It's all here.
When I first submitted ESL go.com to DMOZ, I submitted it as a student resource. I've added over 250 pages since then including a good number of teacher resources. For the past few months I've been submitting changes to DMOZ; I want to be in the "English as a second language" category rather than the "student resources" sub category.
The main reason I care is that this might boost my link popularity; the sub category pages have lower page ranks. The other thing is that I want my sight to be listed appropriately. It's no longer strictly a student resource. However, DMOZ has been ignoring me for a while now.
Anyway, get your category right the first time when you submit to DMOZ (and I suppose this holds true for the Yahoo! directory as well) because you may never get a second chance.
So ESL go.com is #51 on Yahoo and #66 on Google for ESL. That's a bigger discrepancy than I would have expected. Clearly Google is the more important search engine however; In the 5 dyas of February so far, I have over 1,000 hits from Google and around 400 (a bit more) from Yahoo!.
In my previous entry and comment I mentioned that I seemed to have settled at 80, but then "ESL go" went to 78 for the search term ESL on Google. Now, I've gone to 69. Now maybe the google dance hadn't really finished and it's still winding down, or maybe the time visitors spend on a site is really important in Google's formula for determining rankings.
I read somewhere that if you click on a web site after doing a search, the engine monitors to see if you come back to the search results. If you do, then the site you clicked on didn't have the information you needed; it was a bad search result. If you don't come back, then you must have found what you were looking for; it's a good search result. I wonder if I moved up 12 spaces by clicking on my domain (I only did it 3 or 4 times) and not going back to the listings? Probably not; seems too good to be true. But I think clicking and not going back to the listings can certainly help.
http://www.seo-search-engine-ranking.com/ad_network_222.php