google frowns upon follow links for reviews and giveaways and you can lose your page rank… no follow code is like this… Say i have a site to be reviewed….I give you free online access to the site.(which could cost you 50$ otherwise) ......

Dofollow Software

One of the best SEO tools we've used is Dofellow.
you can download this software here

It finds dofollow blogs, and helps you comment in them in a very easy and friendly user interface. It is actually a blog commenting tool that saves you time by filtering out the nofollow blogs.

By commenting in dofollow blogs you can get a lot of free incoming links and improve your ranking in search engines. It is the one of the most powerful way to get back links.