Newspapers online have always struggled with a consistent business model. There have been registration walls, paid content behind walls (including columnists and archives), and various ad schemes from paid search ads to classifieds to interstitial ads that bar entry. Many of the paid content ideas have fallen aside lately, with the boom in online advertising. dropped its not-so-popular TimesSelect pay wall for its op-ed columnists, and Rupert Murdoch is leaning toward tearing down the Wall Street Journal Online’s paid wall as well. So the question remains: If online newspapers decide to rev up advertising, what happens if there’s a cyclical downturn in ads? What revenues do they rely on? What content would you pay for on a newspaper site? Older archives? Specialized news alerts? Customized feeds? Nothing? Share your thoughts in the comments below and I’ll publish the best ones in a future Your Take Roundup.