er, post-it notes? Stick a couple round the house, like the bathroom, the kettle etc. They can be obscure if you like, as long as you know what they mean, they needn't say "CLENCH!"
Or for a more high tech option, sign up to google mail then use their calender (it's like a free version of the O2 joggler if you ask me!) you can set all manner of reminders which can send free texts through to your phone or just pop up on screen when you go on the pc.