Wordtracker is another service that requires an annual subscription to utilize all of its features. Their database is made up of 330 million search terms, collected from the major metacrawlers, Dogpile and Metacrawler, and is updated weekly. The search data they show is a record of the number of times the exact keyword or phrase has been searched in the United States over the last 365 days. As in the case of Keyword Discovery, this difference in default keyword matching type causes Wordtracker to display search volumes significantly lower than what Google’s tools show.

2) SpyFu: I suggest to have paid account on SpyFu. I just need to find my competitors who using Adwords and review them using this tool. It will show me what ads and keywords they are using. Note that my competitor who paid for that particular keyword knows exactly that it is important for his business including recent trends. Also using SEO feature you can input any URL and find our which keywords they are ranking for.
You can also filter by query, which is useful when looking at branded queries, or when looking at specific words. For example, only show keywords that include the term "SEO". The graph also allows you to spot trends in across the available metrics and compare week-on-week or month-on-month. This can help you to drill down and monitor progression over time, allowing you to answer questions like "have my branded keywords received more clicks in the last month compared to the previous month?", "has the CTR improved?", "did average positions in Google improve?".
One possible problem is that although the Keyword Planner has some cool new features (including integration of the Google Traffic Estimator, which will be retired too), as of this writing, the indispensable Exact Match and Phrase Match features are nowhere to be found! Whole books will become useless without these, so I hope Google will eventually port them to the Keyword Planner. Nor do you see the “Include specific content” option, which is a life-saver for the adult industry, which spends the most on Google PPC.
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).