szehau

Default Trackbacks is a wordpress plugin that sends trackback to the preset URLs. It is enhanced version of the old Default Trackback.
Features:
<ul>
<li>Send trackback to the URLs in the list when a post status is changed from “any” to “publish”.</li>
<li>Configure the trackback URLs under WordPress?s admin setting page.</li>
<li>Default setting for sending trackbacks (to send trackbacks by default or not each time publish a post).</li>
<li>Option to override default setting above at edit/new post page.</li>
</ul>

Default Trackbacks

This plugin will send trackbacks to URLs in the list ONLY when user publish a post or change the post status to publish.

scottsm

For a while, I’ve been a bit annoyed with WordPress losing pings (those automatic links on your blog when someone links to you) anytime someone links to more than one of my posts. It turns out WordPress’s comment flood prevention is getting in the way. This plugin prevents WordPress from discarding these pings.

WP_PingPreserver

Prevents WordPress from eating pings that come too quickly in succession (i.e. a single post linking to more than one of your pages).

Default Trackbacks vs WP_PingPreserver