I have created my wordpress blog named c-ationClick Here (I'm not advertising the my blog but, just telling you about it). It's new and has not yet much content. I was thinking of using Google Adsense on it. I have a category of "Website Reviews" inside the "Reviews" menu. I was thinking of posting some posts on Websites as if I was reviewing them for my users. So, when I'll post a review of any website; should I take permission from that very website to post its review on my website or is it not legal to post reviews of website without taking permission from its owner. I want to ask the same thing about other categories and Gaming Reviews. Also tell me, will it also be legal on Google Adsense because I do not want to earn illegal money!
So, please help me!
Anxiously waiting for your replies

You don't need permission from web sites to post reviews, if you did then no one would be able to give bad reviews. I don't know about Google Adsense.

Of course you don't have to ask for permission to give your opinion on something, whether on a public website or anywhere else. That's an essential part of the "free" in "free speech". You can speak about anything to anyone, express any opinion you want, and you can offend people as much as you like too (pretty much anything short of a direct threat to someone or some people is allowed). But you also have to accept that someone might write a review of your website, saying it's garbage. That's the deal.

Unless you're in a country that doesn't respect the most basic human rights, there isn't much you can say or write that is illegal or worthy of any retribution.

Also, if writing website reviews, you are also allowed to grab graphics / screenshots from the website and put them up on yours as examples of what the site looks like. This is called "fair use". As long as you are not practically "stealing" their content to replicate their functionality on your site or something like that, you can grab bits of their graphics for your own fair use of it, with no need to ask permission.

As for Adsense, that is different since this is an association, and as per "free association", Google has the right to choose not to associate with you. Google certainly won't require seeing the content of your website before agreeing to have you use Adsense, but they reserve the right to pull out if there are complaints or bad press or for whatever reason they want, but my guess is that your site would have to be pretty horribly disgustingly offensive for Google to pull their Adsense from it.

So Mike 2000 17, you are saying that I have the right to post review on any website without their permission. But, what if I want to grab some images from some others' website to mine and then post the image with my own content; will it be legal or not?
Also tell me if, suppose, I am writing a website review on Daniweb, I'll sure be writing it in two to three days, will I be allowed to post the daniweb header image in my review as an image of "How it looks" .
What if I also want to embed someones' youtube video into my own blog. Should I take the permission from its owner?

Yes, as I said, this is "fair use". You are allowed to grab some graphics and screenshots of the website to show "how it looks".

And yes also for embedded youtube videos. That's why youtube has the embedded video feature. As far as they are concerned the more visibility they get the better.

As far as Google Adsense is concerned there are some rules to follow.

From what I can make out, what you intend to do is;
1. Write the review for Site X
2. Post the review on Site X
3. Link back to your site
4. Link your site to their site

Now, Google may construe this as using Site X to increase your traffic and therefor your Ad income. I don't think this is allowed anymore. Additionally, you will need to host some content and not simply be a link catalog.

I haven't used Adsense in a while and Dani might be able to clarify, but make sure you read all the Terms and Conditions and be sure of what you're signing. You're entering into a contract afterall...