What are the ‘Ping’ URLs for each search engine?

Question: What are the ‘Ping’ URLs for each search engine?

Answer:

• Ask.com: http://submissions.ask.com/ping?sitemap=#URL#
• Google: http://www.google.com/webmasters/sitemaps/ping?sitemap=#URL#
• Bing: http://www.bing.com/webmaster/ping.aspx?siteMap=#URL#

The Yahoo ping URL no longer works. It was discontinued by Yahoo as part of their organic search merger with Bing.