I have website in English. I would like to translate this web in 6 languages what will be better for optimization create new domains and link them from main site or create subdomains? Please, take into account that all webs are in different languages and I want to optimise each language independently for example google.de for German version, google.es for Spain and so on
Using same domain name for different language sites seems difficult task to me, I think it is good if you can register domain names of country specific tld preferably hosting in same country rather than using sub domains. Also consider to get listed in local directories/search engines of those specific language countries that you're going to target. For content you need not to worry for any duplicate content as you are going to translate it in different languages.
I personally would go for one site preferabley a .com then use subdomains such as uk.wbesite.com and es.website.com an so forth. Main reason i say this is that you will the have just one site to concentrate on promoting rather than 10 or so, definitely DO NOT do what a lot of people to and put one of those automatic site translation scripts on you site that uses google or yahoo to translate the site as they are hideously slow and very unreliable. If it an ecommerce site, oscommerce has some great options for using different languages on one site... Just an idea.