when you say "indexing a new site in google", are you referring to how to go about getting the site into the index, or how to improve the site's positioning once it's been indexed?
For getting a site into the index, the best way I've found is with a sitemap.xml file - Sites that used to take weeks to get indexed are indexed within a couple days. And if I add new pages to a site, I can re-submit the sitemap.xml file and have the new page(s) indexed just as fast.
Once the site's indexed, getting it up in rankings (if you've got all the standard SEO work in place) it's about building those links back to the site. So in that case, social networking helps a lot, if you can devote the time to it. Submitting press releases through sites like PRWeb.com (their SEO capable submissions) can generate hundreds of links back when done properly. (Though these links tend to fall off after a few months so submitting three - four releases a year is important...)
In my blog I go into a lot of this in more detail.
Hope this helps!