Anything "purchase" I make. I'm the kind of guy who would rather go without, or drive a piece of shit used/free product into the ground, than buy something of middling quality. I get much more enjoyment and satisfaction out of one high quality item than I would two mediocre items that together add up to the same cost. But specifically computers. I only buy one once every four or five years, but when I do I make sure it's a beast and will take abuse for the next half decade.
I'm generally a tightwad, but there are certain items that we I (we) splurge on. Food is at the top of the list. We still try to buy food that's on sale, but generally I'll spend the extra money for a t-bone with good marbling over a cheap cut of steak. Why have chewy dairy cow when you can have cow sashimi. Our weekly food bills typically end up around $250, and its only two of us. Likewise, when we go out we generally spend $200~$300 for a dinner. We only go out once every couple months, but I'd rather spend $200 at a sushi restaurant instead of $80 at East Side Marios. The worst offender is cheese. I'll drop $7 on a brick of 4 year old cheddar vs. pinching pennies and buying some orange plastic cheese. My latest obsessions is blue cheese, specifically Stilton blue cheese. Technology wise, I tend to be a "buy-and-hold"; I aim for the upper level stuff without getting too crazy but hold onto it until things change sufficiently. Until a year ago our main TV was a Sony rear projection HD television, which we'd had for close to a decade. Now we have a pair of Sanyo 60" Quattron LCD TVs. So I splurge, but only once decade.