We lived in Banda Aceh, at the far end of Sumatra, for a year from summer 2006 to summer 2007. This experience is covered in the Aceh Diaries, technically not a travel blog, but with enough references to different places to warrant inclusion.
Individual locations we came across, during work and travel, on Sumatra can be accessed below, or through the article Berestagi to Bukittingi, which described a trip from North to West Sumatra in December 2006.