I frequently don't like images showing up in my RSS feeds. To me, RSS is a quick way to read just text. So, I used a custom stylesheet to tell Safari to hide images in RSS feeds (images on web sites will still display normally).
Use a text editor like TextWrangler (free) to make a new file. Paste in the following:
@charset "UTF-8"; .apple-rss-article-body img{display:none};
Mac OS X Hints
http://hints.macworld.com/article.php?story=2011030917302344