A comment (with backlink) on an edu blog could be very beneficial for your SEO.. so why do people not utilize this fact more? There are many thousands of blogs hosted on edu sites just waiting for your comments (obviously, keeping 'em on-topic, informative, and non-spammy!)
Just searching Google for:
(your niche here) blog site:*.edu
can put you well on your way to getting higher quality backlinks from blog comments. Using the advanced search to get more recent results helps too.