Used to always be adult pron and gambling were good for money (even with tons of competition), but... ...only if you want to build your rep in those fields.
That's too general of a question. And it'd be better to ask 'what industry has the best return annually'. Still too general though. There really is never one type of website that "makes the most money". There shouldn't be. Proxy websites are a flooded market, but they're still always in demand because they're always getting banned by filtering networks and what not.
I wouldn't say proxy sites are the MOST profitable, but they do pretty well. I think the key is to offer something to your vistors that need/want so that they return to you over and over again. If you can automate it - that's even better.
I think dating sites are doing real good this days. Other social networking sites like myspace etc etc are also money making machines!
It all depends on how the site is marketed and how it stands out from other sites. Right now interactive sites are whats doing the best. ex. Myspace, Digg, Youtube ect.
I'm looking at some of these directory owners and amazed at their ability to sell links for $10 or $20 a piece, so I'd say them!
Directory sites can sell links for much more than that... of cause you have no idea however if their "sponsored" links are actually paying businesses or ones that are being given free sponsorship to make others think that people are paying $100 for a link. There is potential in anything, but as usual it is down to the business skills of the owners.
Many people search porn..and they accidentaly or they temtate to click the images and link that ads by google..so you may get many click..
i don't think anybody is going to tell you any specific hot niche out there, so maybe the best thing is do a lot of research, try to find out what consumer/people want on the net build a website site and market it as aggressive as possible, if it fails try again.. and one day hopefully you should hit something that makes some decent profit.
Gosh! The ones making the most money will always be the ones with the highest market share, no matter the industry. It's not what you do, it's how well you do it that counts. Google do well. Amazon do well (are they making any cash yet?). I bet you there are some of those jackass proxy sites with banners all over them that do pretty damn well too. Not Google-well, but still.