Peenie Wallie

http://rpc.pingomatic.com/
This pings the following sites automatically, so you do not need to add any of these if you are using the ping0matic address -
Weblogs.com
rpc.weblogs.com/RPC2
Technorati
rpc.technorati.com/rpc/ping
Blo.gs
ping.blo.gs/
Blogrolling
rpc.blogrolling.com/pinger/
Blogbot (Danish)
blogbot.dk/io/xml- title=”Remote Procedure Call”>RPC.php
Yahoo
api.my.yahoo.com/RPC2
Rootblog
ping.rootblog.com/rpc.php
Weblogs.se (Swedish)
ping.weblogs.se/
Bitacoras.net (Spanish)
bitacoras.net/ping/
Weblogues.com (French)
www.weblogues.com/RPC/
Blogg.de (German)
xmlrpc.blogg.de/
PubSub.com
xping.pubsub.com/ping/

As well as:
These are not included by pingomatic, ao add these in as well -
http://ping.rootblog.com/rpc.php
http://www.mod-pubsub.org/kn_apps/blogchatter/ping.php
http://bulkfeeds.net/rpc
http://xping.pubsub.com/ping/
http://ping.bloggers.jp/rpc/ (Japanese)

Update: Added http:// before the url's to prevent "URL must be absolute" errors.
Update: See subsequent post here related to pinging URL's with blog entries.