In order to offer a choice in offered feeds through WordPress, I have made some very slight modifications to the wp-rss2.php file and in the options inside WordPress to make that possible.
Setup your feed option (under options->reading->syndication feeds->full text) to show full text as the default feed for your blog. This way, the feeds are more complete and links are not disguised etc. Now you can download wp-rss2e.phps (rename it to wp-rss2e.php) and put it in the root of your blog. Once there, just create a link called “Excerpted feed” somewhere in the sidebar to link to that file (or anywhere else really, just not within the loop) in order to allow people to subscribe to the excerpted feed.
You can also add it to the <head> section of index.php as well if you choose, but this is not necessary. If you want the default to be an excerpted feed, this process will not work for you.
