Hi - do you recommend to put a nofollow attribute to the affiliate links? Besides not "draining power" of your other links, could it be....

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.