I have an old fashioned diary that fits in my handbag and I write all my appointments and definite commitments in there, eg Welsh group, online Skype session, dog walking, visits to Dad. Then I tick things off when they've been done or add a note saying why I didn't do whatever it was.
The more personal stuff is a list of Things Done in a little spiral bound notebook. This helps with the depression because having a huge To Do list makes me feel overwhelmed and it helps to be able to look back and see that I am actually doing things. I list very mundane stuff, down to the level of "emptied kitchen bin", "put the recycling out", "did a load of washing". It is, literally, a list of things done each day.
Finally there is my Journal for Venting. That's a blank hardback notebook where, if I feel the need, I pour out any anger or sadness in an often pretty incoherent stream. I haven't actually felt the need to do that for quite a while, but it's there if I need it.
And of course I have this LJ, which is where I put things that I hope may interest my friends as well as making an online diary for me to look back at. I also use LjArchive to make an offline backup on my own computer.