The suggestions and points you have made a really useful. I am really happy. Not everything is working 100% as I'm still working on the site, I felt stuck on the layout and design. I'm changing features constantly.
I'm thinking of inserting a small description of the site in the top part of the sidebar, or in a box above the articles. I've been suggested to add a popup such as wefollow's one http://wefollow.com/, but I'm not sure if it's a good idea.
Thank you for pointing out the problems about the terminology I used, I haven't thought about this and you have given a great explanation on why and what you suggest me doing.
About the "tweetmeme" and "reddit" boxes, I applied the theme colours for each one. I'm thinking of maybe only displaying theme colors when a relevant container is being hovered, although this might disrupt the user's attention.
I'll also change the text contract, and level them a better. I'm thinking the following order of importance: - Title - Description - Domain, Source - Time ago, Poster, Options
I'm a little undecided if to consider the description more important than "domain" and "source", or the other way round.
I'll add a footer asap!
Thank you mschaecher, this was top advice!