Regardless of the state of the economy, it's a given that the Internet will continue to grow. It's also true that revenue should grow from both e-commerce and online advertising. That's because the percentage of advertising going online is increasing at the severe expense of print advertising, television advertising, and so on. Online commerce is expected to experience double-digit growth as well.In 2006, Internet retail sales were up 24% year over year. 2006 was also the first $100 billion-plus year for e-commerce, with overall online retail sales coming in at $102 billion for the year. Online advertising is expected to go from $18 billion in 2005 to $24 billion in 2006 and still be a single-digit percentage of overall advertising, implying there's heavy growth ahead. So I believe it's worth taking a look at the stocks behind the top 20 biggest Web sites in the world, ranked by unique users last month. The first couple of stocks are obvious, but there are some surprises on the list. I've written a lot about Yahoo! ( YHOO) in the past, so I won't go into all my reasons for being bullish on the stock. But the fact remains that it's the most popular Web site in the world, ranked at No. 1 with 117 million unique users. And that doesn't even account for the fact that it owns several other names on the list, including Geocities.com (with 21 million unique users), which came in at No. 19. Yahoo! owns a host of other up-and-coming popular sites, such as flickr.com (the best photo-sharing site), MyBlogLog.com (the fastest-growing social network for blogs) and del.icio.us.com (the best social search engine). And don't forget hotjobs.com and Yahoo! Finance (the largest financial Web site with 12 million unique users). Don't count Yahoo! out just because it lost search. The biggest Web site in the world -- and growing -- is going to do well this year. Google ( GOOG) is, of course, No. 2 on the list, with 108 million unique users.