For marketing your site, I think you could make a Firefox extension that gives in-browser suggestions for similar sites. That would be so useful. In fact, I believe a browser addon would be the "most convenient form" of this idea.
I played around with Firefox extensions three years ago and submitted a very niche addon for fun. Within the first week it received 10,000 downloads and ultimately downloads went up to 100,000. That was only possible because Mozilla would feature newest addons on the front page with no lobbying efforts required on the developer's side. Three years ago, there were a couple of links near the middle of the Mozilla page to the newest addons. Now, there is a link to sort by "recently added" near the top of the page, so visitors are one click away from seeing the most recent. Also, there is a sort by "recently updated" option. I remember people frequently updating and seeing their extensions remain in the "most recent" section.
For finding similar sites, I personally use xmarks and similarsites.com. (Fo)xmarks obviously has a firefox extension. Similarsites.com has an extension with around a million downloads; don't know if the chicken came before the egg, though.
You could bundle some functionality into your addon like quantcast/alexa/pagerank data push it as an SEO tool.
An ironic usage of your website just occurred to me:
1. Use google to find a couple of marketing/seo blogs/websites.
2. Input these websites into moreofit.com to find more marketing/seo sites.
3. Email list of found sites about moreofit.com and how useful it is for marketers. Describe how you found them using moreofit.com.