Make Sure your Blog Posts are Pinged Automatically

One of the hidden features in Windows Live Writer is the ability to automatically ping (send a signal) to popular blog aggregators every time you publish something to your blog.  This feature actively pings the servers of the blog aggregators you specify and to indicate when there is new material.
To do this in Writer, click on Ping Servers in the Options dialog (Tools, Options, Ping Servers).
Add the names of the servers you want to ping, for example, some popular search engines are:

You can also use a pinging service like Ping-o-Matic (this service will automatically ping a number of popular sites for you). Just put the following in the list of ping servers:

What other servers should I add to this list?