LINKEDDIRECTORY.INFO (a directory site, use phpld free or paid version) PASSWITH.INFO (a password site) RAPID-LOADER.INFO (either a rapid share premium link generator site, rapid share search engine site or possibly a image/file uploading site) SITEFAVICONS.COM (a favicon generator site, or maybe a social bookmarking site)
LINKEDDIRECTORY.INFO = Web Directory PASSWITH.INFO = Flatulance? RAPID-LOADER.INFO A site to test load speeds of websites SITEFAVICONS.COM Favicon generator, or favicon tutorial, or site for placing favicons with links to the actual peoples websites, bit like that guy who started off the grid thing or whatever it was, selling space, hey this could be your first million.
articledirectory has provided the best suggestion. But if you don't want to do that much work then host them and link them with your good sites. After next update or so you can rich some PR there. Then you can decide to use them or can sell the domains.
I'll give you 3 suggestions as they're the only 3 things you can do with domains: 1. Park it 2. Develop it 3. Sell it
I say park LINKEDDIRECTORY.INFO and sell the rest. Of course that's given you don't want to develop. If you looking for a developing, develop linkdirectory.info.