Possible Clues:

• Half.com's parent company
• See 31-Across
• Website with the heading 'Recently Viewed Items'
• It debuted the 'Buy It Now' option in 2000
• Site with a "Shop by category" option
• Company that bought (and later sold) Skype
• Memorabilia marketer
• Where some buy used LPs
• Online bidding center
• Website with a Watch list