More content will result in more pages indexed by Google and other search engines.
Google really like updated / new content, so you should always try and keep your site updated with new information.
Its also important to remember that Yahoo can produce 20% of traffic to your site, so check your site performance in Yahoo.
Yahoo Site explorer, provides a very good tool for checking back links to your website.
https://siteexplorer.search.yahoo.comBacklinks have been increased, but why there is no Google Indexed page increase?Your backlinks may all be of low quality, work on building higher quality backlinks with PageRank
Socially bookmark all your pages of your site, that will help with indexing.