What should I do with my old, keyword related domains?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Warren Chandler: I have a two part question for the community.  ;Would love to hear your thoughts if you wouldn't mind.  ;Thank you all.
  
  What should I do with my old, keyword related domains?
  I have a number of very good domain names that are keyword related that used to point to my main website.  ;I'm wondering what you all think is the best thing to do with them now.  ;Develop a mini site on each?  ;301 redirect?  ;I've tested both options for a while and can't seem to find tangible value in either.  ;
  
  Just how powerful is LinkedIn?
  I'm starting to look over LinkedIn of late more and more, but I'm finding it hard to quantify whether it's a worthy SEO move.  ;Is it worth my time?  ;Anyone experienced in LinkedIn and have impressive results?
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  Unique Websites: +Warren Chandler  ;If you have 10-20 connections and complete your personal profile, you can then get a company LinkedIn page; the links that you get from this page are internal redirected + ;nofollow but you can get testimonials on this page. Possibly these testimonials ;might send out good "social signals" to Google - especially as LinkedIn is a reputable site - although the seo experts on this forum are better placed to tell you whether "social signals" from testimonials help your seo. (From my point of view, this opportunity for testimonials is valuable as, for the last couple of years, customers have been leaving testimonials on a popular web design directory - which G has now deindexed and so these testimonials are all (I assume) now worthless; I cannot see LinkedIn getting de-indexed so any testimonials you get there should be for the long-term.)
  
  LinkedIn also has interest groups (much like G+) but you have to join these groups from your personal profile (not your company page) so - imo - joining the groups doesn't drive traffic to your company LinkedIn page. What the groups do do, is give you an opportunity to showcase your top blog posts to members of the group - much as in Google+.
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  Luke Ciciliano: I wouldn't suggest having multiple links going to the same content +Warren Chandler  ;as Google would see it as duplicate content. If you're going to have the old domains point at your current site you should do so through 301 redirects. Remember though that the point of a 301 is to tell the search engines that content has moved. If a domain previously pointed to content than doing a 301 from the domain to the content would be good. Are the various domains all currently pointing at the same content without a 301 redirect?
  
  Linkedin can be a good source of traffic depending on who your target audience is. Remember that Linkedin is more about B2B transactions so if your content falls into that interest area than it can be a great source if used correctly. ;
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  Warren Chandler: Thanks for the information ; +Unique Websites  ;, I already have my page set up, and I am a member of a few groups, but haven't utilised them since I haven't seen any tangible data that shows it's more beneficial than other social media outlets.
  
  +Luke Ciciliano  ;I wouldn't have multiple links or any duplicate content, and there doesn't seem much point in a 301 since the domains have no content there at present - it's essentially just a few decent domain names.
  
  At the moment these domains are used as dev. domains for the many projects I juggle, but I'm really hoping to get some SEO value out of them.  ;
  
  What I am thinking is that I set up one as a personal vcard site also utilising my main site's RSS feed for articles I write.  ;Any thoughts on this?
  
  Thank you again for the replies.
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  Luke Ciciliano: Just be mindful of making another site's RSS the main content on a second site +Warren Chandler . If the second site doesn't have any original content, and is simply importing the RSS Feed, Google would likely view that as "scraped" content and not give the second site much love in search. This wouldn't impact the original site at all. ;
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  Warren Chandler: Thanks +Luke Ciciliano  ;
  
  I'll probably end up just creating a vcard site of my services with some original copy and add some quality articles to it when I have time.  ;
  
  Just seems a waste of some great domain names, but I guess as with everything these days, hard work produces results.
  
  If only there were 77897 hours in the day! :)