If they have page ranks then sell them and if they get good traffic then park them . If you have few which don't have any use then use them for giveaway project and promote your websites or blogs .
If you want to turn them into proxy sites, I can host them all for free - you have your adsense on the front, I have banners on the proxied pages.
If it were easy then we'd all be buying a new domain (or more than one) every day to make $1 from, after a week it's already paid itself off and has about another 357 days before costing anything again, with 100 that's like $35700, lol. Parking isn't really going to work unless you're pulling some majour traffic in from somewhere, even proxies don't really work, people who use web proxies are used to ad placements and are unlikely to click any ads, not saying it doesn't work, but it's not as easy as people make it out to be. As for the blogs etc. and at least one mentioned outsourcing, well I don't know about you but I don't exactly plan on paying like $100 for each of the 100 domains for content, plus hosting, plus new content as the weeks go by.
developing would be the best bet in here create simple sites on it, and sell the 100 sites for like $100 each.. will get you $10k
Mini sites with a lot of ads....fake porn sites? lol...just a page with adult affiliate links, or maybe some sample galleries at most
park them.. give some ads on it.. make some backlink like link it each other.. after they got PR sell it.. buy some domain again