I love Pepys’ Diary, a website that reproduces an entry from Samuel Pepys’ seventeenth-century journal every day, in blog format, with lots of hyperlinks so that you can learn about everything from the buildings of London to the (supposed) medicinal qualities of Wormwood.
There are other interesting predecessors of blogs. For example, I have on my shelf two books edited by G.P.V. Akrigg, A Jacobean Journal for the Years 1603-6 and A Second Jacobean Journal. Akrigg reproduces one real London diary entry for each day of each year in the early 1600s. The entries comment on major events, sensational crimes, foreign and military news, and recent publications. I do not know to what degree the diarists expected their writing to be public, but there was certainly no right to privacy under King James, and these diaries were all deliberately preserved.