"I want to make sure that my web 2.0 pages get crawled by the search engines"
Then forget about pinging and look at links and social signals.
There are cheap tier 2 link blasts on the marketplace, usually with GSA SER, Scrapebox or Xrumer, which are known to work well. Also, you can manually build links to the Web 2.0 sites as if they are normal money sites - directory submissions, article/picture/pdf/etc. submissions, blog comments, etc.What type of links do you suggest that I get for web 2.0 sites? I've never done this and that's why I ask.