Been using serplab.co.uk for a while now for rank checkings, and a feature that they have is note adding. So you can basically add a note in to your rank graph that shows on that date "posted guest post on blog..." for example. I've been using it to see what sort of serps actions happen after certain actions, and couple of times I misspelled my note, but you couldn't change it. I emailed the guys on Thursday, "hey, would really love to see the possibility of note editing?" Got a reply back the next date, they would look into it, Come Saturday, guess what? The feature is now live. Now that's what I call a service that works with its customers. If you havn't changed to serplab yet, do it, you get 300 free searches on the trial account, and the upgrades are so cheap, you can't go wrong.