Starting March 5th, I had decided to put a 1 month moratorium on all the spending except basic necesseties like food and drinks. There were multiple instances during these 10 days where the moratorium saved me from spending, which I would have done otherwise. This is specially to stop spending money on 'impulsive purchases', which are the things that you don't need.
If you feel strongly for buying something, make sure you don't buy it for a few days. It will kill the desire of unwanted spending, and will actually make you happy that the money didn't go wasted. Now, even after a few days, if you feel the need of that item, then you can go ahead and buy it. Most of the time, you won't :).
Following are the list of items I would have bought otherwise:
1. Sony Erricson P910 PDA Phone
2. Building a custom DVR (Tivo)
3. Playstation 2 with Katamari Damacy
So, during this time, I have learned to delay purchasing anything by atleast 10 days. If you can live without it for that time, you probably don't need it.
p.s. I am not sure how long this kind of control will last, and the bubble will burst ;)