I’ve found google trends to be an interesting way to see if a keyword (and by extension a niche) is growing or shrinking, and whether it’s seasonal or not. I can’t think of any other tool out there that can reliably tell you this information, so that’s really useful. Also, if you’re building a site, especially an authority site, getting onto something that’s trending upwards is a fantastic idea.
Wordstream is a free keyword tool that makes it easy and fast to get those keywords that your business needs most in order to drive traffic through paid and organic search.  All you need to do is enter a website URL or keyword and you will get hundreds of relevant keyword results that are tailored to your country or industry. Every keyword has an estimated CPC, competition score, and a proprietary opportunity score that will assist you in budgeting for your online campaigns. You can download your list in a CSV format and upload it in AdWords directly and begin to work on your new campaigns.
How do I know this? Because I’ve done it! In late 2013 I was still struggling to earn a respectable income online. I started up a keyword research service and marketed it to just this blog audience. It turned out to be quite popular. Basically – I would find niches using Long Tail Pro then create Keyword Research Packages. Each package contained usually several hundred keywords with KC scores calculated. I was selling these packages for anywhere between $97 to $147. I even sold one single package for $597! That one had very high search volumes and very low competition.
The limit on manual keywords could be higher.  I personally wish we could input 10,000 keywords at a time, instead of 200.  However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input.  Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).