For the way I DM 4E, all I need is some bullet points, some quickly-drawn maps (I draw them out at the table on one of those wet-erase mats, so it HAS to be quickly-drawn), monster stats, and an idea in my head.
In fact, here's an example of my actual notes from a pivotal moment in my current game. I have only removed the monster stat blocks and magic item text. This is an entire level of adventuring.
Encounter 1: Boarding the Fishing Boat
Fisherman Trapper x2 (150xp)
Fisherman Gutter x2 (175xp)
+1 Gutter Party>5
Encounter 2: Sinking the Warship
Fisherman Hunter x3
Fisherman Line Spikers (x6)
Fisherman Butcher x3
+1 Hunter +1 Spiker Party>5
Adventure Gain
+2 Sacrificial Longsword
Blackleaf Gloves
1355 GP
Encounter 3: Beachhead
Twig Blight x4
Twig Blight Swampvine x2
+1 Swampvine Party>5
Encounter 4: Hungry Forest
205 GP mixed amber, pearls, seashells (acting as a lure)
Twig Blight Swarm x1 (200xp)
Twig Blight x4 (500xp)
Twig Blight Seedlings x4 (200xp)
+1 Swampvine Party>5
Encounter 5: Rotweed
Rotweed x1 (350xp)
Twig Blight Swampvine x4 (450xp)
+4 Twig Blight Seedlings Party>5
+2 Sacrificial Longsword
Encounter 6: Orc Patrol/Gathering Party
Battletested Orc x3 (450xp)
Orc Archer x1 (175xp)
Orc Savage x4 (175xp)
+1 Battletested Orc Party>5
On Archer:
50gp Alchemical Reagents (Arcana)
50gp Mystic Salves (Heal)
50gp Rare Herbs (Nature)
50gp Sanctified Incense (Religion)
Encounter 7: Lady Zill and the Nest Guard
Battletested Orc x3 (450xp)
Orc Archer x2 (350xp)
Lady Zill (175xp)
+1 Battletested Orc Party>5
On Lady Zill: Ornate Silver Dagger (755gp), Blackleaf Gloves
Encounter 8: The Shadow Dragon’s Lair
Majestrix (400xp)
Battletested Orc x4 (600)
+4 Savage Orcs Party>5
On Battletested Orcs: Black lacquered battle axe (100gp)
Only book I need to keep on me is the rules compendium, and that almost never gets taken out. I barely even use the GM screen that I keep up.
To me there's not much 'game' there - it just looks like a linear series of fights and treasure parcels!

Was there a map that could be explored, or was it really as linear as that? Reminds me of the big pile of WoTC adventures I have that are literally linear strings of encounters.