Found via Marginal Revolution, this quote sums up the value of (essentially) blogging for yourself in academics:
But the Harvard economist [Dani Rodrik] finds the blog — short for Web log — useful because it serves as a reference catalog for his ideas. “I now constantly Google my own blog for ideas that I knew I had at some point,” he says. “Previously, the ideas would have come and gone. The first good thing is that I have them a little more developed, and, secondly, I can actually recover them.”
Every once in a while I run across a blog that says something like “sorry I haven’t been updating for a while”, which I think entirely misses the point. This blog is meant mostly for myself, as a reference tool for things and ideas I come across. A lot of people wouldn’t consider this to be a true blog because of the sometimes lengthy delays between posting, but the point is to support research in the areas I’m interested in, which can be pretty narrow admittedly.