U.S. smartphone users spend an average of more than 4.6 hours per month browsing the Web, according to M:Metrics (now part of comScore). Mobile browsing increased 89 percent year after year -- from March 2007 to the same month this year -- while page views increased 127 percent.

Which site was the “stickiest” on mobile phones? Local classifieds sensation Craigslist garnered the top spot with an average of an hour and 39 minutes -- the longest duration of any site among the top 20 domains visited.

By comparison, in the UK, smartphone users spent an average of nearly 2.5 hours a month browsing. Facebook was the hottest destination with an hour and 45 minutes at the site.

In the United States, Facebook ranked fourth in time spent browsing, after eBay and MySpace, respectively, with Disney’s Go coming in at No. 5.