10. ESPN
> Pct. of all time spent online: 0.6%
> Desktop visitors: 38.7 million
> Mobile visitors: 34.6 million

Based on unique visitors, ESPN is the 23rd largest digital property in the U.S., according to comScore, and the highest sports-related property in the country. ESPN has made a push into mobile during the past year. Between December 2011 and December 2012, mobile engagement based on unique visitors grew 59%, more than any other of the top 25 Web properties, except for Pandora Media Inc. (NYSE: P). ESPN currently offers 13 different mobile applications, including SportsCenter Feed, to get up to the minute “news, scores, video and audio,” along with the company’s Fantasy Football and Fantasy Baseball apps.

9. Craigslist
> Pct. of all time spent online: 0.7% (tied for 8th highest)
> Desktop visitors: n/a
> Mobile visitors: n/a

Craigslist claims that more than 60 million people in the United States visit its sites each month, leading to 50 billion page views each month. But while people tend to spend a hefty amount of time searching through apartment listings, job openings and personal ads on the site, Craigslist has yet to roll out a mobile application for either smartphones or tablets, leaving third-party Craigslist applications to fill the void. The company only recently released mobile-friendly features such as a map view and an image-heavy grid view of all its offerings.

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8. Tumblr
> Pct. of all time spent online: 0.7% (tied for 8th highest)
> Desktop visitors: n/a
> Mobile visitors: n/a

Tumblr is not among the 25 largest Web properties in the United States, but those who go on the site spend a lot of time there. Consuming 5.7% of all time on social media, more time is spent on Tumblr than any other social media property, except for Facebook. Lipsman of comScore noted that Tumblr really took off in the past year and continues to grow each month, particularly among those ages 25 and under. He noted that Tumblr’s growth has been more organic, rather than by overt attempts by the company to increase engagement. Notably, the site has become popular for fashion and humor blogging.

7. eBay
> Pct. of all time spent online: 0.9%
> Desktop visitors: 77.7 million
> Mobile visitors: 39.5 million

EBay Inc. (NASDAQ: EBAY) has benefitted from the large growth in online retailing. In the fourth quarter of 2012, revenue in the marketplace division — the e-commerce segment of the company — grew 16% compared with the same quarter in 2012. EBay also owns PayPal, an online payment processor. The service generated $1.54 billion in revenue during the fourth quarter of 2012, an increase of 24% compared to the prior year. PayPal processed roughly 700 million payments during the quarter and had 123 million users. Like most of the top digital properties, the use of eBay on mobile devices has grown rapidly. Between December 2011 and December 2012, mobile engagement based on unique visitors has grown a solid 23%. The company has been working to get more people to use its service on tablet devices. CEO John Donahoe has publicly said that people are more likely to purchase items on a smartphone or tablet than on a PC.

6. Amazon
> Pct. of all time spent online: 1.0%
> Desktop visitors: 128.2 million
> Mobile visitors: 80.5 million

Similar to eBay, Amazon.com Inc. (NASDAQ: AMZN) has been a huge beneficiary of the increase in online retail purchases. During the most recent holiday season, sales conducted by a third-party on the website were up 40% from the same time in 2011. Amazon also is directly challenging Hulu and Netflix Inc. (NASDAQ: NFLX) with its Prime Instant Video service. The streaming service has added new movies and TV programs to its portfolio in recent months. Amazon on Thursday announced that shows from the E.W. Scripps Co. (NYSE: SSP) network of channels — such as HGTV, Food Network and Travel Channel — will soon be available through the service. Amazon has made significant inroads in mobile usage as well. More than 80 million people in the United States accessed an Amazon site through a mobile device in December 2012, higher than all Web properties except for Google, Facebook and Yahoo!