Don't forget a composite longbow and multiple types of arrows. Helps to overcome DR, and if you lose your quickrazor blade it's easy enough to stab with an arrow using Iaijutsu Focus.
A barrow or cart with a donkey, to carry large amounts of gear from Point A to Point B.
Rope. Lots and lots and lots of rope. And a grapple and pitons, just in case. Also, string.
Several empty flasks, made from various materials. Clear glass, steel, lead, etc. You never know when handling various liquids can come in handy.
Lots of blank sheets of paper or parchment, and a carrying case. From forged documents to scribbled notes passed across the dinner table to explosive runes
traps, they're quite useful.
Plain-Jane daggers. Good for wedging doors shut, as weapons after you've gotten disarmed, as makeshift pitons or if you need to climb down a wall in a hurry when there's a tapestry or somesuch nearby (thanks, Errol Flynn!), or when hammered through a plank and concealed under leaves as quick-and-dirty trap for pursuers. Very useful stuff.
Chalk is great for leaving messages for companions when you're off scouting. Scribble an arrow on a wall or tree, or work up some kind of simple symbol-code for when you're being pursued but need your party to follow in your footsteps. If you're using D20 Modern/Future stuff, crush it to powder to help with laser-based traps.A big lead sheet.
A block of pure sodium. Gotta love those violent (al)chemical reactions. ^_^
The standard 10-ft pole.
An adamantine bowling ball. Nothing says trapfinding like a spheroidal pin-pusher.