The Etsy Sellers Blogroll is a list of seller blog links that can be posted on any blog/site with a small snippet of code. If you become part of the list this means you have more links to your blog thus a higher ranking in search engines. For example, if there are 100 links in the list, then 99 other blogs are linking to your blog.
This not only helps to promote you individually, but also Etsy, which means more people will hopefully learn about it and join the marketplace as possible buyers.
Learn more and join here: http://www.etsysellersblogroll.blogspot.com