I have done a lot of impulse buys over the last few years. I have my on and off times. I would go a couple months where I don't buy anything, and my expenses are pretty low. Then there would be a set of months where I'm buying whatever's interesting that comes my way. ;_; I haven't made any "impulse buys" since last summer. I just made one a couple days ago importing a DS lite right after mr current DS broke. ;_; Impulse buy. $180. Basically paid $50 more to get it a month earlier and for a different color (but then again, I wouldn't be able to make purchases like these next month). Hot. I will say it was worth it.
A couple years ago I went on a classic gaming (more like SNES) collecting spree, so I spend hundreds getting classic SNES games. Last school year, I remember buying basketball cards on impulse.
Oh, I also tend to go to concerts on impulse. I usually end up going on craigslist to get last minute tickets and stuff. Even my trip to LA for the first Dear Friends concert was impulse.... and I went to it during my final exam week.
Jam it back in, in the dark.