I have seen number of times that very high traffic web sites use a trick sometimes when they want to mention a website or a resources (images etc) but do not want to give direct link. At first instance it look that it is for tracking a link but I think the story is different.
If redirecting is just for keeping track of outgoing link then that can be done through Google Analytics or some other tracker service also. Here I feel this can be done for saving the endorsement done indirectly by giving a link to other site. When you link to any page on web then in SEO term, web page is endorsing the work present there. So, indirectly it is a credit leaving out of your page.
For example, just visit at this article. It is a very nice article about Design Pattern. Check there and you will find few images for each section of the article. Those images are used from different source. Credit is given to all those images that are used from different sources. It is mentioned like Image courtesy of http://www.xyz.com. Please click on any of those link and you will find that they are going to somewhere else first than to the mentioned link there.
I have checked those websites and few are of very low page rank and Alexa rank. So, if nettuts mentioned those link directly then they can be benefitted directly in SEO terms as well. Now, here comes few points to think about:
1. If I have using other work or resources then we should mention it and give credit back for those part.
2. How much credit those pages mentioned deserve. How much is the worth of those work or resources on the web?
3. Others. Like how to mention to those web pages (owner) on my web page.
Nettuts is a very high ranked sites and it is visited by large number of users. It is a very high traffic site. Nettuts has mentioned the link (origin of image) right below the image. So, it has mentioned the owner of the property at very prominent place. Link is clickable and user may be visiting there as I have visited to few. Those pages got new visitors. Now, should nettus give link (link credit) to those pages or not! Considering the type of article and the resource used, I think what nettus have given is enough. So, nettus can avoid giving link credit.
How it has done that? Given credit for work but saved from leaking out lots of SEO credit to low worth web sites?
- It has mentioned the link at proper place thus giving credit for the work.
- It has not given a direct link to those pages and thus saved from SEO page credit leak.
Right Click on the link and just cancel it. Then again mouse over the link and you will see that links original page currently set. Now, I am not sure whether this kind of link is giving credit to the mentioned page or not. I think as at first, link mention directly to target website (whom tutsplus want to give credit for work), so search engine may be giving the credit. Search engine may not be good that it can think of event attached to any particular link! If they are getting the link credit by search engine then point that it is saving link credit in the given example do not prove well. But I have seen those kind of links at other sites that redirect to intermediary site first before going to desired place and mention the intermediary address also in href, but Currently I am not in a mood to search for those pages. So, I do not think you believe that points mentioned above are not good. But the points I have mentioned should have given you good insight about the link and SEO and it may help you thinking about the redirecting service or method. Thanks for being so patient and reading the whole article.