Here at Chez Necessity, I keep track of all the money we spend. I use Quicken, and it arranges all the entries into different categories, such as gas, groceries, clothes, etc. I started keeping track of expenses (all of them - if I put a quarter in the meter, I need to enter it) about 10 years ago, and it is certainly an eye opener. I began writing down everything I spent in a little notebook (this was a real pain, and Quicken is SO much nicer) because I kept looking at all these ATM withdrawal slips and had absolutely no idea what we had spent the cash on. I would recommend that everybody try it for a couple of months, if only to see where all the money goes.
Another good thing about Quicken is that it lets you compare this month's spending with the prior month, or the same month last year, or pretty much in any combination you want. This helps keep us in line, and allows me to analyze where I might be able to cut back a bit. As everyone's pocketbook knows, I am definitely seeing large increases in both gas and food. Food is partly our doing, as I've switched to more and more organic products (including milk, which almost physically pains me every time I pour out a glass) and our farm share started in June. I was fretting over the grocery bill (we're up to about $85 a week for our family of four) and I came across this link about what the rest of the world eats. A little perspective is always a useful thing.