Well, if you are doing link building then you should use both, nofollow and dofollow sites as we need natural links and these would make natural links for your site.
@kristoffDec 19.2012 — #yes i agree with you. actually what we're doing for our link building is to have this ratio 45% to 65% of dofollow nofollow links. then 35% to 65% of keyword citation and link dropping... do you think this is an effective strategy for our site? we're developing services for web, any suggestion?
@Steve_SmithDec 19.2012 — #Nofollow refers to a link attribute that allows website owners to tell search engines that a particular link does not confer credit to the target site. The site is crawled but not indexed in google's index.While it's a no follow link you cannot get the link juice.
Do-Follow link has a great value to all search engines and to increase Google page rank o-follow links are very helpful. If you want see your site in the first page of search engine then you must increase do-follow links.If its a dofollow link crawler can crawl that link and some link juice can be passed.