How do you keep track of blog posts you keep meaning to write, but don't?
mlLK: Keeping track of something that hasn't yet happened (at least in terms of blogging) sounds a little frivolous. Maybe you just don't have anything to say? Try approaching it as  PG does, post an extrapolated anecdote. (aka an essay, see: http://news.ycombinator.com/item?id=369141) Otherwise start from square one, pick up a good book on the writing process and don't even worry about blogging, and instead focus on writing as a craft in it's own.