NEW YORK ( TheStreet -- Black Friday may be in full swing, but online retailers are eagerly anticipating Cyber Monday, hopeful of a major revenue boost as consumers cautiously re-open their wallets. Cyber Monday, the Monday following the Thanksgiving holiday, is the e-commerce equivalent of Black Friday, traditionally marking the start of the online holiday shopping season. Keen to gain any advantage in a cut-throat economy, however, retail's biggest names are stretching the concept of traditional shopping 'days'. Online retail giant Amazon ( AMZN), for example, launched its Black Friday deals page earlier this week, and will start offering its 'Cyber Monday' deals on Sunday. Even brick-and-mortar companies are overhauling their online efforts, with J.C. Penney ( JCP) expanding its 'Cyber Monday' sale to two days, starting on Sunday. Retail giant Wal-Mart Stores ( WMT) is also offering an entire 'Cyber Week' of offers on its Walmart.com Web site. Wal-Mart spokesman Ravi Jariwala told TheStreet that the 'Cyber Week' promotion encompasses more than 100 products, most of which will be revealed on Monday. Amazon rival eBay ( EBAY) is also launching an online shopping offensive, recently announcing '12 Days of Deals' starting on Black Friday. The San Jose, Calif.-based eBay also unveiled a special 'deals' application for Apple ( AAPL )'s iPhone and iPod touch devices earlier this week, and expects that more than $500 million of eBay merchandise will be purchased via mobile devices by the end of this year. Almost 90% of retailers will have a promotion for Cyber Monday, according to the National Retail Federation's Shop.org division, up from 83.7% last year and 72.2% in 2007.