Are you looking at a one script - with multiple domains pointing at it solution?
That's what I'd sugest/offer. (Maybe a handful of such scripts if the domains could be grouped - for example geographically, or separating "community" type domains from "retail" for example).
I'd make it expandable - starting with something which worked soley on the basis of the domain name itsself then for domains with potential or traffic you could add keywords / content / content feeds, spending resources where they're most likley to generate a return.
For sites where applicible I'd go for attempting to build user-generated content for example through a directory / forum.
You might want to be careful with domains you primarily intend to make money off by reselling. I would note though that previous use even as a parked page can put off buyers. (Especially if that parking is one that essientially produces adsense/affiliate spam pages - which result in search engines excluding the domain - I can't see any harm in a plain Sedo parking)
What's your budget?
What are your plans?
Any solution will probably need a copy writer - ideally one who knows the subjects involved - are you looking for an inclusive one stop shop.
Any solution once implemented will need maintainance.
