A couple of RSS submission pages mentioned by Blogging Pro: Brain Bliss network's Feed Shark and Thomas Korte's Feed Submission Service for RSS feeds.
Feed Shark could use some instructions: what URL is expected, why do you have to add that code to your page (and to which page), how can you suggest new sites? Also, submitting to all 20 sites in one step would help.
Not sure if these two scripts provide any extra features compared to Ping-o-Matic. Since WordPress uses Ping-o-Matic out of the box probably there is no need to use these scripts if you run WordPress.
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