Long Tail Pro by Spencer Haws is the most useful keyword research tool that you can use for your internet marketing. Thousands of webmasters depend on the tool to generate thousands of keywords. It is such effective that it has dominated the keyword search market for the few years it has been into existence. It would cost you less than one hundred dollars to have access to this important life-changing tool.
In a nutshell, Long Tail Pro helps you quickly find keywords in bulk based on a seed keyword that you input. In addition to returning hundreds of related keywords, the tool also shows search volume (monthly search volume), advertiser bid, number of words, rank value, and my favorite Keyword Competitiveness (helps you judge the competition and keyword difficulty).