It's very hard for me to leave the house without something to record my daily thoughts in.

I love the pocket-sized composition notebooks for that, usually. Unless I'm going, say, for a walk in the woods, then I just take a full notebook and carry it and sit down and BAM! words on a page. I've been known to leave myself long voicemails when I've been driving and unable to stop and write, but then my phone service changed the way it did voicemail, so now I have to leave myself long private-locked voice posts on LJ, haha.