The value of links split over a portfolio of single-purpose websites is questionable. SEO is a Winner Take Most game, in which having 1% more ranking ability (in general, links) than the next guy can result in you getting 50% more traffic, or more, because of how people click the highest positions in the SERP overwhelmingly more. In other words, there is an increasing marginal return on links <i>pointed at the same domain</i>.<p>Thus, splitting your links over 5 or 50 or 500 properties tends to mean you rank for a LOT less than you would have had you "put your eggs in one basket", even if you get marginally more links in aggregate to the portfolio than you would have gotten to the single site.<p>The only exception to this which jumps out at me is exact match domains, because they can rank with many, many less links than an identical page on non-exact match domain. (For those who are new to this concept: if your query is <i>exactly</i> [exact match domain], then exactmatchdomain{.com|.net|.org} and a few major country TLDs get an automatic and <i>massive</i> bonus in their rankability <i>for that query and that query alone</i>. My main domain has thousands of links, many from fairly authoritative sources like e.g. google.com. My mini-sites on exact match domains generally start with one link from my blog and outrank the main site within a week or two.)