There does not seem to be anything unusual with (what is alleged to be) Anders Behring Breivik 's facebook and twitter page. The facebook page has been taken down, don't know by who, but it is still visible through google's cache. The twitter page, only has one tweet, apparently a quotation from J.S. Mill "One person with a belief is equal to the force of 100 000 who have only interests."
Among the books featured is "On Liberty" (from J.S. Mill) and there is also Orwell's 1984. It looks like that he is a gamer (world of warcraft) and a fan of Caprica and Stargate. But some said this page is quite new, so probably not that accurate to be used for profiling.
I still fail to comprehend what motivated him to do such horrible things.