Here is the ping list that use when setting up a new site which is powered by wordpress. This would include any wordpress express site.

To add this list into your site, simply login to your site as you normally would, then:

Navigate to Setting > Writing

This will show all the writing setting for this blog.

At the bottom of this page, there is a section called 'Update Services'. This is where you add the ping list.

Press 'Save Changes' and you are done.

Here is the Wordpress Ping List:

http://rpc.pingomatic.com/
http://blogsearch.google.com/ping/RPC2
http://ping.blo.gs/
http://ping.feedburner.com
http://ping.myblog.jp
http://rpc.blogbuzzmachine.com/RPC2
http://rpc.technorati.com/rpc/ping
http://rpc.weblogs.com/RPC2
http://www.blogpeople.net/servlet/weblogUpdates
http://audiorpc.weblogs.com/RPC2
http://ping.fc2.com/
http://ping.myblog.jp/
http://blogs.yandex.ru/
http://ping.blo.gs/
http://rpc.bloggerei.de/
http://www.feedgy.com/
http://blogsearch.google.ae/ping/RPC2
http://blogsearch.google.at/ping/RPC2
http://blogsearch.google.be/ping/RPC2
http://blogsearch.google.bg/ping/RPC2
http://blogsearch.google.ca/ping/RPC2
http://blogsearch.google.ch/ping/RPC2
http://blogsearch.google.cl/ping/RPC2
http://blogsearch.google.co.cr/ping/RPC2
http://blogsearch.google.co.hu/ping/RPC2
http://blogsearch.google.co.id/ping/RPC2
http://blogsearch.google.co.il/ping/RPC2
http://blogsearch.google.co.jp/ping/RPC2
http://blogsearch.google.co.ma/ping/RPC2
http://blogsearch.google.co.nz/ping/RPC2
http://blogsearch.google.co.th/ping/RPC2
http://blogsearch.google.co.uk/ping/RPC2
http://blogsearch.google.co.ve/ping/RPC2
http://blogsearch.google.co.za/ping/RPC2
http://blogsearch.google.com.ar/ping/RPC2
http://blogsearch.google.com.au/ping/RPC2
http://blogsearch.google.com.br/ping/RPC2
http://blogsearch.google.com.co/ping/RPC2
http://blogsearch.google.com.do/ping/RPC2
http://blogsearch.google.com.mx/ping/RPC2
http://blogsearch.google.com.my/ping/RPC2
http://blogsearch.google.com.pe/ping/RPC2
http://blogsearch.google.com.sa/ping/RPC2
http://blogsearch.google.com.sg/ping/RPC2
http://blogsearch.google.com.tr/ping/RPC2
http://blogsearch.google.com.ua/ping/RPC2
http://blogsearch.google.com.uy/ping/RPC2
http://blogsearch.google.com.vn/ping/RPC2
http://blogsearch.google.com/ping/RPC2
http://blogsearch.google.de/ping/RPC2
http://blogsearch.google.es/ping/RPC2
http://blogsearch.google.fi/ping/RPC2
http://blogsearch.google.fr/ping/RPC2
http://blogsearch.google.gr/ping/RPC2
http://blogsearch.google.hr/ping/RPC2
http://blogsearch.google.ie/ping/RPC2
http://blogsearch.google.it/ping/RPC2
http://blogsearch.google.jp/ping/RPC2
http://blogsearch.google.lt/ping/RPC2
http://blogsearch.google.nl/ping/RPC2
http://blogsearch.google.pl/ping/RPC2
http://blogsearch.google.pt/ping/RPC2
http://blogsearch.google.ro/ping/RPC2
http://blogsearch.google.ru/ping/RPC2
http://blogsearch.google.se/ping/RPC2
http://blogsearch.google.sk/ping/RPC2
http://blogsearch.google.us/ping/RPC2
http://ping.blogs.yandex.ru/RPC2
http://ping.kutsulog.net/
http://ping.rss.drecom.jp
http://rpc.bloggerei.de/ping/
http://rpc.odiogo.com/ping/
http://rpc.reader.livedoor.com/ping
http://rpc.weblogs.com/RPC2
http://services.newsgator.com/ngws/xmlrpcping.asp
http://www.blogpeople.net/servlet/weblogUpdates
http://zhuaxia.com/rpc/server.php

I hope this helps you with your online business adventures!