There are many people who swear by Market Samurai. It's a little on the pricier side. I think it helps to have a bit of a grasp on what you are doing before buying it.
There are a lot of tools out there, but they're just tools. I've seen many get into the mindset that if I buy this or that, I'll make money online. There is no magic bullet. You have to develop a plan first. You have to have some idea of what you are doing and what you are trying to accomplish.
Programs like Market Saurai and the ones I mentioned at Incansoft are fantastic. There are also programs like SE Nuke and BruteForce
SEO that will automate a lot of your
SEO work.
Really though they are just time savers. I think it is best not to spend too much money until you know what you are doing. Plus, if you are doing all your work yourself, it makes you appreciate what these programs do for you and just how much time they are saving you.