RSS Feed Submission is the best options to improve ranking, If you have a blog, then submitting to all these rss directories will help in that within minuets of publishing a new article to your blog, loads of links are created automatically to that new post. This really helps get your new post indexed very quickly and spreads the word around the internet, but don't forget to put so-called auto discovery code for your RSS feeds in your page head source code - there are bots (some legit) out there looking for feeds:

<link rel="alternate" type="application/rss+xml" title="RSS" href="http://URLOFYOURFEEDINRSS" />
<link rel="service.feed" type="application/atom+xml" title="Atom" href="http://URLOFYOURFEEDINATOMFORMAT" />


TOP RSS AGGREGATORS:

http://www.blogdigger.com/add.jsp (PR7)
http://www.feedage.com (PR6)
http://www.blogstreet.com/bsibin/add.cgi (PR6)
http://publisher.yahoo.com/rss_guide/submit.php (PR6)
http://www.plazoo.com/en/addrss.asp (PR6)
http://www.feedbite.com (PR5)
http://www.rssfeeds.com (PR5)
http://feedraider.com/ (PR5)
http://www.feedsubmitter.com/ (PR5)
http://purerss.com/addfeed.php?catid= (PR5)
http://www.unclefeed.com/rss/addfeed.html (PR4)
http://www.feedsee.com/submit.html (PR4)
http://www.feed24.com/?c=add (PR3)
http://www.feedfury.com/ (PR3)
http://www.goldenfeed.com/AddFeed.aspx (PR3)
http://www.feedooyoo.com/ref.htm (PR3)
http://www.feedest.com/feedAdd.cfm (PR3)
http://www.rssmad.com (PR3)
http://www.feedbase.net/Add.php
http://www.rssmicro.com/?m=fs#theForm
http://www.rssmotron.com/feed_eater.php