Why .edu backlinks are great for SEO
Created in 1985 as one of the first top-level domains, .edu was originally intended for universities and educational institutions anywhere in the world. During the 90?s, some non educational persons or organizations managed to get a .edu domain, such as england.edu, which is a commercial site.
In 2001, registrations of .edu domain names has been restricted to post-secondary institutions and organizations that are accredited by an agency on the U.S. Department of Education's list of nationally recognized accrediting agencies.
Due to the fact that .edu domain can't be registered by anyone and are reserved to educational institutions, many SEO experts thinks a backlink from an .edu site is good for SEO, because Google is seeing the .edu site as a serious source.
While it can be tempting to pick up my list and post quick messages on the listed .edu sites just to get a backlink, I'd like to insist on the fact that spamming has never been a good SEO technique.
You should pick up 1 to 2 sites per day, read one or two blog entries from each site, and leave an useful, non spammy comment. Remember that SEO is a long distance run, not a sprint.