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Tags and categories can cause duplicate content. If it causes a penalty or not, I don't know.

On smaller sites I've seen the same page listed in the top ten search results for some of my sites. I think this is exactly what Google doesn't want.. I love it but I think Google won't.

I use a plugin on my WP sites called Platinum SEO that allows me to mark tags and categories as noindex, follow. I'm not sure that's the right thing to do but i do it.

I started doing this after noticing i had a lot of duplicate titles "warnings" in Google Webmaster Tools.

Long ago, I read where a Google employee said that if your website has links to the same content Google would not penalize you. That is basically what a tag or category is. Being paranoid though and seeing the duplicate titles in Webmaster Tools, I started dong that just to be safe.

I had a digital camera site take a beating on Google this month. It is slowly coming back up. I had noticed I had more than one result on page one in several cases before I got the smack down.  I had failed to setup my categories and tags as no index in the plugin mentioned above. I have no idea if that caused the spanking Google gave me. The articles were 80% original but i had pulled some content from Amazon without re-writing it so that might have caused it.. I really don't know. Its a fairly new site and I've seen that before so it might just be the Google dance.  Rankings are now improving I went to number one to number 53.  Back at 15 now.

For the "report" you go to the on page option in the menu at the dashboard. You should have that there. If there is nothing there by default, try clicking on the sub menu for report card and you can enter any URL you like in there. It needs to be for a keyword you've setup for one of  your sites though.

I find this tool best for finding out what my competition is doing in regards to links.  Where are they getting them and then I try to get them from the same place. That way I pretty much match anything they do plus I have my own links. I just go after their links with the highest page authority.

I've only been in for three weeks but for keyword research I like SE Cockpit.  It frankly rocks. It has an API interface for SEOmoz so I get some moz data there.  I just don't get the link information that I need. For that I'm coming here.  This is a great tool to monitor your rankings and monitor your competition. You do that by setting up your competition in moz. I think in the link analysis.

I hope that helps.