Use them as affiliate sites. They have a nice Web 2.0 sound to them but the unless you have a really cool idea you want to develop and implement then just use them as lander sites.
Once again they do have a catchy sound to them, worth maybe 10-30 on ebay if you put up some good sales copy and document some of the similair web 2.0 style names that are huge sites on the net.
Good Luck