Is it ok to put links on following sites to increase my site value, if yes then how can I manage to get them? http://www.smartertools.com/ http://acquia.com/ http://www.freerepublic.com/ http://www.prwatch.org/ http://forums.xkcd.com/ http://www.podcastalley.com/ http://habsinsideout.com/ http://www.nydailynews.com/ http://www.enaca.org/ http://www.gamepro.com/
Of course you want links from those sites. They're all very high PR, trusted sites. Getting the links is the difficult part. You could post on the forum to get links from your signature but I don't know about the other sites.
still helpless to get the site owners attention..please let me know some more ways to get linkback from above sites.
It's not surprising that these sites don't pay any attention to your questions. They are way ahead of their competition and probably don't have the time and the interest to answer such requests. Try to get links from weaker and newer websites first and continue with your strategy step by step. If you are consistent in 1-2 years you may get their attention. Something that is worth trying is to ask them if they offer paid links. The answer (if any) will probably be negative, but it won't hurt to try
It is always good to link with authority websites. However, you should know the ways how you can be linked with these websites. These website would not respond to your request until they would be sure that you are worth linking with their websites.