Crisco Candle for emergency situations. Simply put a piece of string (or wick) in a tub of shortening, Use a chop stick or a stick,tie a knot on the bottom and push it down, and it will burn for up to 45 days.... who knew?
The Envelope System--for budgeting your paychecks and staying on budget. This was actually how I saved up $630 for a computer and $350 for a new aquarium at the same time... then I stopped doing it. Maybe I should start again.