I just checked my Quotations blog ( PR #1, Backlinks are 110 as per Google Webmasters, 30 as per Alexa )and I found the number of back links ( both do follow and no follow ) increased a lot. I added a list of sites from where I got backlinks. So lets get started.

Assuming You can register and add a link 1 minute, You can get 8 good high quality do follow backlinks from these sites. I have already got them for my blog. You can check them on Alexa.

SITE	PAGE RANK	COMMENTS
ted.com	8	Register, add Your link in profile.
weheartit.com	6	Register, add Your link in profile.
bubblews.com	4	Register, add Your link in profile.
technorati.com	7	Register and verify Your site/blog.
plus.google.com/	9	Place Your link in profile.
youtube.com	9	Link Your site to Your channel.
pinterest.com	9	Link Your site to Your channel, upload photos from your site.

List Of Sites To Get High PR Dofollow Backlinks: