Marketing with Blogs / Bookmark Sites

With blogs being the latest way for people to express their skills, opinions, and views why not use blogs to market your company. There are alot of companies on the net that allow you to bookmark sites as well as feed them to an RSS file for others to gain your latest likes and information. Here is a list of blog / bookmark sites.
Del.icio.us
Technorati.com
Wists.com
Feedburner.com
Kinja.com
Rojo.com
Newsburst.com
Bloglines.com
Furl.net
Stumbleupon.com

By using the blog / bookmark sites you can share your RSS feeds with others. Think of it as a free way to market your site because the only real thing you invest is your time. However if you are looking to advertise your site or blog on other blogs there is the other way of doing it which is to pay for advertising through BlogAds.com. If you happen to know of any others similar to this topic please feel free to add a comment.