Once you get your WordPress blog/site up and running, create a page and set it to 'private'. Call it something like 'notes' or something similar, and keep all of your site related to-do's and other items on it, adding, deleting, and revising information as you go. You can consider it a simple wiki to keep track of that site maintenance stuff without having to open up a separate site somewhere.
For example, if your site is example.com, your private wiki page would be example.com/notes, then just keep a link to that whenever you're working on your site. Edit as necessary as you go.
I realize this isn't a completely original idea, but it just came to me as I was working on my own site earlier today. Most of you already probably do something similar, but I wanted to pass it along just in case. :-)