Now, I'm aware that this stuff is probably old-hat to a lot of people here, but I figure there are always people just starting out for whom this might come in useful. Plus I've always been of the belief that there is more than enough abundance to go around for everyone, so there is no harm in sharing everything you know.
Oh, also sadly my post count is not high enough et to post actual links But an easy google search of the name of each thing will easily take you there. I promise to come back and add the links when I get the ability to.
Anyway, here goes:
Google Keyword Tool:
Can't argue with the daddy of the internet... it's the only place that I know of where you can actually get a peek into Google's real numbers.
Yahoo uses its data to publish articles based on what people are looking for the most, and they conveniently let you filter them by topic, such as Business, Health, Politics, Tech, Lifestyle, etc.
Lycos (a search engine which used to be top stuff on the net but which has since been outshined by Google) keeps a "music count-down" style list of the 50 top search terms, but more importantly also keeps a running commentary on why these terms are where they are, why they rise, why they fall.
AOL Hot Searches:
Similar to Yahoo Buzz, they publish information articles with topics based on what their data (and for AOL its A LOT of data) shows them people are looking for. For example the headline article right when I'm typing this is: "Trying to remove your scar?" Tadaa, instant need-based niche right there.
You type in a word and Google tries to complete your thought, based on what other people have already typed into it before. Very good for brainstorming.
From the center of shopping and spending on the entire net, ebay freely shares the lifeline of what people actually look for when on their page, which is to say, when they KNOW they're gonna be spending money.
Dogpile SearchSpy: & Ask IQ:
These two might be a bit less useful as they are straight top-whatever lists of searches, but never hurts to have some more of those plus useful for crazy brainstorming.
A final note, I used to worry a lot about competition and KEI and all that, but gradually I've found it doesn't really matter. If there are a lot of people who need what you're offering, and if your offer is good and real, they will find you. People "shop around" a lot on the net, and a person in search of a solution may click on someone else's link today, and some other guy's link tomorrow, but eventually they WILL get to you, and if your copy and your offer rise above the others', you will get the lead and the sale. That doesn't mean you don't have to promote and do your SEO of course! But if there are people who want what you need and if they are willing to lay out the cash to get it, just go for it I say. The idea is more important than the actual keywords.
Anyway, hope this is helpful for guys starting out out there. And thanks to the Warrior Forum people in general for all the help they've given me over the years.