I've shown up to gigs with a snare drum and brushes. I had this thing with a guitarist and bassist at La Costa resort in San Diego and the schlep was pretty long and one day I said "screw it" and took in a snare, snare stand, throne, and some brushes. At first the guitarist was a bit taken aback but after we got grooving things were all right.
Sometimes you have to really get outside your current scenario to really "get" what playing drums is all about.
If you look at it from the absolute bare essentials aspect, really all we need are sticks. You can tap on two or more surfaces and create a musical statement.
But as afar as "normal" gigs go my drumset is a 4pc. 20" kick, 10" rack, 14" hanging floor tom, a 13" snare, and I use one ride, two crashes, a china (right side up, like a ride)and a set of hats. And gotta have the cowbell!!!
This tour (currently out with Tubby- check
www.myspace.com/tubbyfunk for dates) I brought a 5pc but that second tom has not even seen the light of day.