It is called link popularity. Also look to swap links with sites in the top 30 results of a search under your key phrases. For example, Aol owns Excite. Excite is the default search engine for anyone using Real Player the most popular tool for listening to audio and viewing videos on the internet. Microsoft owns Snap and Newhoo to name a few.
Search engines use a tool called a spider.
It visits your site from whichever page you submit and crawls your website through links found on that page. Basically, if the spiders do what they are supposed to do, then the majority of your site will be indexed. However, it is not a bad idea for you to submit your important pages to the search engines just in case the spider takes a year to reach your site. Make your other websites link to your main website. It is very beneficial to have multiple avenues to our establishment.