The SEO Black Hat blog has a good list of sites to ping from your blog. At the moment I’m only using Pingomatic but I’d been interested in hearing from others if they’d recommend some of these sites or others not mentioned.
The list
http://rpc.pingomatic.com/
http://www.a2b.cc/setloc/bp.a2b
http://api.feedster.com/ping
http://api.my.yahoo.com/RPC2
http://api.my.yahoo.com/rss/ping
http://www.blogdigger.com/RPC2
http://www.blogshares.com/rpc.php
http://www.blogsnow.com/ping
http://www.blogstreet.com/xrbin/xmlrpc.cgi
http://coreblog.org/ping/
http://ping.blo.gs/
http://ping.feedburner.com
http://ping.syndic8.com/xmlrpc.php
http://ping.weblogalot.com/rpc.php
http://www.popdex.com/addsite.php
http://rpc.blogrolling.com/pinger/
http://rpc.technorati.com/rpc/ping
http://rpc.weblogs.com/RPC2
http://topicexchange.com/RPC2
http://xping.pubsub.com/ping/
http://api.my.yahoo.com/rss/ping
http://api.moreover.com/ping
http://rpc.icerocket.com:10080/
