Want to make your RSS feed more attractive? Featured Image In RSS Feed is a simple plugin does exactly what it says – it automatically adds your posts’ featured images to your feed.
Here’s an example of what a plain RSS feed looks like:

After you add the Featured Image In RSS Feed plugin your feed will look something like this:

You can also choose the size of the images added in the plugin’s settings page. Please note that your theme must support post thumbnails in order for this plugin to work. Obviously, you will also need to make sure you assign a featured image for each of your posts if you want them to have images in your feed.
I can’t guarantee that having featured images in your RSS feed will get you more clickthroughs, but it will certainly make your feed nicer to look at. You can get the Featured Image In RSS Feed plugin for free from the WordPress plugin repository.
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U r awesome Sara
Note: This plugin link no longer exists in the WP plugin repository (as of 7/19/2012.)
I’m also looking for this in WP 3.4.2 as of 9/13/2012. Any other plugins that will put post thumbnails in the rss-feed?