There’s a nice exchange on ether wave propaganda that’s come out of their series of analyses of Schaffer’s oevre. The posts (part one; part two; three to come) are about two of Schaffer’s papers from 1993 dealing with the historiography of (history of) science. My main point—so far—has been to keep in mind whether the audience ascribed to Schaffer (or even the audience he claims to be talking to) is really the target of the pieces.
I think the larger series of posts this is a part of is a great example of what can be done with blogs: long form, continuing analysis that isn’t restricted by journals or edited volumes, and that evolves in dialogue with it’s audience.(Jon, maybe this is a partial answer to your question about what people might blog about.)
Feel free to pitch in!