M0zilla.org: fan site with comparisons to explorer. Audience will likely be webmasters, so emphasize how it displays sites properly, the way they were meant to be displayed. Post about new extensions that come and review them. You can discuss aaron wall's great seo extension for instance, which is amazing for competitive intelligence.
Traffic: webmaster forums/blogs/newsgroups, esp the site review forums where you can emphasize how it looks in mozilla. Mozilla/explorer/netscape/opera help forums, groups. Trackbacks when you review a new extension. Interviews with program developers, extension developers, others in the mozilla community. Everyone loves to show off their press (don't let too many people in on this one, but it's a real goody

Usually gets a nice link too, and if you interview the right people, that's a pr7-8 link). And if you've got the skills, why not write an extension yourself?
Costs: Hosting, design, paid posting in other forums, time for following mozilla news, participating in forums, etc. plus the writing. Use an RSS newsreader to cut down your research time.
Monetization: Firefox referrals! The problem is, how do you monetize repeat visitors. See if you can sell CPM adspace once you've gained a following, to other forums, to extension developers who want to launch a new extension in style, to webmasters with related content. If you write your own extension, offer one with fuller features (things that will really increase productivity) for download at a price. Free lifetime updates of course. I'll be honest: monetizing this one's tough.
BTW: gangsters.ws would be a great rap culture domain, or alternately mob history site. affiliate ads for the godfather movies

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Escortes.mobi = escorts in spanish? If not, you can make it a escort service site for people with bad grammar

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Seriously though, I see it as a directory. Escort services get listed with you so they don't need a mobi presence. Phone and email posted a la finditincanada.com (.ca?). Pay-per-call/email? Or you can try setting it up with a chat room and all deals agreed to there earn you a commission. Like, if NP were running it, you buy namebucks, go to the chat, transfer $xxx to the escort, and NP takes a % of the xxx transferred. The other side of things is that escorts can cash out the np for real $.
A friend started a blog directory by contacting people directly and suggesting they submit their site (free) to the directory. 20% response rate. Even better is to point out a way they can improve the site in the email, and mention 'design tip/fix' or something similar in the subject line.
As to promoting... yellow pages ads? Porn site ads? Ads whereever horny males congregate. This includes football games. Or fantasy leagues. But better to advertise when they're thinking of sex, so try swingers' forums and all that.
Costs: design, advertising (try to also have them mention on their site that they're listed with escortes.mobi), hosting, chat set-up, namebucks system set-up.
dreamsearch: affiliate for miss cleo and other astrology/prediction co. 'get your palm read over the internet darlin' "...my psychic powers tell me you're a lonely teenager with no credit card! get going sweet'art" Cheap traffic from second tier PPC engines (domain traffic i'm told).
Monetization: You can go for ppc arbitrage or for affiliate ads. Test it out and see what works.
Costs: design/template. Might want a few to see which works best. Traffic. No one types in dreamzsearch, though I guess you know that. Hosting that can handle lots of traffic staying for short periods of time. You'll probably be in the red for at least a few weeks (making some cash but not covering costs is my totally unprofessional guess), so you should budget for that, and even longer. If you can afford to test it for two months that would be ideal.
devnerds. since we don't need another dev forum, why not make this a dev culture site? nerdiness is cool! every developer is king in his own ip address!
content: tech news + toys, dev articles, webmaster conferences, thick glasses, pc video games, techno music, san francisco and silicon valley politics/news/weather etc.
monetization: sell merch? zen t-shirts advertising the wearer is an Uber-nerd. laptop cases and coffee mugs. there are plenty of places that can do this for you as a private label thing online, and you guys split the profits.
costs: hosting, design, content.
promo: newsgroups/forums covering any of the topics you discuss on the site. seo for the word 'nerd.' You're not going to rank for dev, i hate to break it to you, unless you spend 40-50K+ on SEO. you can also go for a wealth of long tail terms that are related to nerds, and development. Maybe you and m0zilla guy get together?
Sorry about this one, i just really don't know much about what could appeal to self-identified "nerds."