In addition, you can dig into the paid side of search and find out what keywords your competitors are bidding on, and then leverage those keywords for your own organic benefit if you're not already doing so. Search Metrics does this as well, but I've found SEMRush to provide a greater range of keywords and they save more historical keyword data than Search Metrics.
2) SEMrush- This tool offers fantastic competitive research around domains to find what keywords could be driving traffic for your competitors. Looking at paid keywords ad spend can also help you know which keywords might have monetary value worth pursuing organically. If a competitor is willing to spend a high ad budget on terms and you think they do a good job running their ad campaign, then its a good indication it is worth organic ranking effort.
If you're struggling to think of more keywords people might be searching about a specific topic, go to Google.com and take a look at the related search terms that appear when you plug in a keyword. When you type in your phrase and scroll to the bottom of Google's results, you'll notice some suggestions for searches related to your original input. These keywords can spark ideas for other keywords you may want to take into consideration.
Note: the old software version of Long Tail Pro would have spit out several hundred adwords suggestions (many being irrelevant to the seed keyword) for this one seed keyword and then you would have to filter to see only what you wanted to see. With the new cloud version of Long Tail Pro, you set it to show only a certain number of keywords and it displays the most relevant keywords so you have less noise and confusion to filter through.
As for the history of the company, as I explained, I created Long Tail Pro back in 2011. At the time, I was creating tons of niche sites and was doing alot of keyword research and content creation. I was trying to figure out what types of keywords would rank quickly in the search engines, specifically Google, and I was frustrated with the other keyword research tools (in particular Market Samurai) out there.