a couple other ideas

* auto blogging ... install wordpress or get a blogg*er account and purchase/get a auto blogging software and you are set
* create a forum with vbullitin, phpbb, etc .... you'll need to work hard on getting the initial content but after that, its more or less auto-pilot
* setting up a dig*g like site using the pligg template

once again, it all boils down on the niche you choose and how well they are seo-ed