Different domain names for different markets - you might also want to reference your site by different names in order to target different markets. You could, for example, have a site about search engine optimization and want to target both SEO and web designers. Thus domain names like seo.com and webdesign.com would make sense.

www - Any good webmaster knows his or her site needs to be referenced with and without www.

Okay, so what's smart thing to do? Well, it is possible that search engines do compare a limited number of pages to check for duplication. They could certainly check if someone reported something, and they might check directly linked pages (although this is still a heck of a lot of overhead for very little benefit).

Of course, Google and other search engines can account for a hefty percentage of traffic received by a site. In fact, sometimes number can exceed 70 percent. So it's wise to spend some time ensuring that you are totally clean when it comes to search engine optimization. In other words, a technician from any search engine should be able to examine your site down to it's smallest detail and find no evidence of any kind of search engine spamming (attempting to get higher rankings by unethical means). This is absolutely critical to a site's survival for long term.

Keeping that in mind, here's what I tend to do.

Multiple domains - Using multiple domains to same site has a tremendous number of advantages. Thus, I tend to follow advice given by others: take advantage of permanent redirection. In other words, set up a redirection (a 301 status code) which simply tells browser "this page has moved, proceed to this page, and move is permanent. This tells spider about redirection with no possibility of misunderstanding, yet allows for multiple domains.

Republished articles - I allow others to republish many of my articles, and at this time I have records of over 10,000 of them all over internet on thousands of web sites. This is not a problem, as these articles are sent in text format. The webmaster must then drop this text into his site, which requires some reformatting and shuffling around. Thus, finished articles may have same text but formatting is very, very different. This is a highly respected method of gaining a large number of incoming links: I give you something (an article, i.e., content) and you give me something (a link back to my site).

Mirroring - I haven't needed to do this yet, so I have no advice as to what to do if a site requires actual, physical multiple versions of itself. I would tend to just do it overtly (out in open) and not worry about it.

Chris: "Yes you are right about JavaScript. There is also a cookie place on their browser that keeps track of people that come take a look and return later to buy."

Question: What if someone is using both PPC and SEO program. How is cost is distributed? Do we have to plug in cost for each program to calculate ROI?

Chris: "If all you want to track is SEO, just don't put code into entry pages you use for PPC or use separate PPC entry pages. The same is true for PPC. You can separate these by only placing code into unique pages you use for PPC."

Question: So for conversion, we need to create two conversion pages: one for PPC and one for SEO?

Chris: "No, just differentiate entry pages. You can use same conversion page."

Question: How do we know if it's right keyword that generated a lead since people browse from page to page?

Chris: "The entry code is placed in all pages search engines are referring visitors to. This way Keyword Tool will track entry and watch to see if it converts into a sale. You can place code in just one page or as many pages as required--there is no limit. You can even have same code in an include file in your template. This way KeywordTool watches refers from all your pages."

Question: Do we need to do data entry for keywords and PPC?

Chris: "There is no data entry; KeywordTool looks for keywords as they are used on search engines, not how we think they should be used. This way you can discover good keywords you got listings for and didn't know it."

In Conclusion

If your ROI is important to you, which is should be!, KeywordTool (http://www.keywordtool.net) will certainly help you determine your conversions rates and return on your investment for any traffic through search engines, directories, and pay-per-click engines. It's a sharp program with a lot of handy features.