One tool of sorts is the Adsense bid price 'tool' provided by Google. (I forget the URL.) It provides info on the cost of clicks, e.g., the maximum bid some AdWords users pay. You type in a keyword, and the max you would be prepared to pay; then Google says the top price being paid at the time.

This data, however, is often misinterpreted by newbies. They'll take the info and build sites to target the high-value keywords. Even if they manage to get their new MFA site built and high SERPs, however, the site could, as many MFA sites do, get smart priced.

Then, instead of getting $25/click, they get $0.01/click.

This is something sites selling high-value keywords for Adsense forget to tell you. You will need the high-value keywords, high SERPs, high-value website, and high conversion rate, to get the top Adsense dollars.

If you can line up all those ducks, go for it.

p/g

And even if you do get all those ducks lined up, it's still no guarantee. You just have to work hard and hope that you do well. I find new niches by just studying the Internet, get out there and do some real research.

nice posts p/g and spaceylacie

Trade magazines, university journals and the like for emerging technologies, trends, etc. You might have to plow the ground (read), plant seeds (set up small, on topic website) and wait (for the world, business and advertisers to castch up). That's life. If there was a get rich quick easy scheme that worked we'd all be rich already.

Do you seriously expect anyone to give away trade secrets?

Well the secret is that there is n't any.

For new areas in my niche, I steal a bunch of magazines at the newsstand and get ideas from the ads in there.

It is pretty easy... wear a trench coat.

Even if you find some well paying niches they may well be really competitive. So it's a balance of finding new directions to go that will pay reasonably but not so competitive as to make it impossible for you to do well in the serps with it.

OTOH it doesn't hurt to look to see what the popular niche keywords are and check out how many ads are there on the topic.

I still put pages in that may not do well money wise but give the site more strength. But I also look to see what people are interested and branch out in my niche area in those directions.

I use several tools, including the following online ones.

Overture Keyword Selector Tool
Google Keyword Tool
SEO Tools by SEO Chat
SEO Book Keyword Suggestion Tool
ClickBank Marketplace Search
Black Hat SEO Keyword Discovery
Google Trends
SEO Log's Fake PageRank Detection SEO tool
WordTracker
SpyFu

All are free, or provide a trial period.

Tools only tell you part of the story
Always check the SERPs for how many advertisers appear for a particular keyword, and note the keyword phrases used in the AdWords ads because they may give up some good phrases you may not have thought of.

Excellent andive Webwork:

Trade magazines, university journals and the like for emerging technologies, trends

just open your eyes and ears, and see what's going on in the world around you and listen to what
people are talking about. Say your town or area is plagued by potholes, to me that is begging for site
with geocoded google maps of all the potholes. Articles on the effects of potholes to vehicles, fixing the damage yourself
etc etc. Maybe a forum for people to discuss and complain about the potholes. There's an unlimited supply of niches and themes that are sitting in front and around you right now you just have to actually look and not glance.

My advice only applies if you are going to build a website that adds value to the net. I don't know that it would work for scraper sites.
Anyway... Unless you are going to build a large or complex website that will take more than a couple months to launch, I suggest that you pick whatever topic interests you, do a search in an SE and look at the "sponsered results" to make sure there are plenty of advertisers, if so then build it.

Another reason I don't believe much time should be spent researching high paying niches is that just because some people get $5 per click for a certain keyword, it certainly doesn't mean that you will too.

Another reason is that a high paying niche is likely to have more competition. It may take you 3 times as much work to get good positions for a niche that pays $1 per click as it would to get good positions for a niche that pays 33 cents per click.

I have created a few sites thinking they would be good money makers and they often are, but the sites that make me the most money are not the ones I would have expected.
That's my 2 cents.

I'm with SincerelySandy - pick stuff that you are going to find interesting.

The problem with what some do, is they end up spending a lot of time building a site (being that if it's competitive, it's going to require a lot of content), however because it's so competitive, the payoff is not as good and it becomes a you put in X amount of time for Y amount of profit when you could have put in X/2 amount of time and made Yx2 amount of profit" on a much less competitive niche.

I have lists of things I find interesting/fascinating. Every now and then I'll go out and do a "survey" if you will, of said topics. If it seems that interest is picking up for some reason or there is some big development on the horizon, and nobody is the "go-to" site, or if there are "go-to" sites, if there is room for another, I'll go for it.

I look at the sites I've done because they are sites that I thought should have existed and didn't (i.e. sites I'd visit) and I look at the sites I've done simply because they'd be a cheap buck, and the difference is huge. The ones where I'm really interested tend to do much better over time.

Are there any legitimate tools out there to help find high paying adsense niches?

Google.

Can't say how legitimate it is, though.