tedster - 8:54 pm on May 21, 2011 (gmt 0)

If you have even a glimmer of their future purpose, I'd put some on-theme content there. If they are exact keyword domains of some kind and you're generating significant ad income while they're parked, that would be the only situation where I might do otherwise.

If you have even one piece of great content you put there, I'd say start aging the home page and potentially attracting backlinks.