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.
The five-dollar savings plan: Every time you find yourself with a five-dollar bill in your possession, you set it aside instead of spending it. At the end of the year, you use the money you've saved for either a big purchase or to do something you wouldn't normally spend the money to do.