Being a Model 18 fan, I thought I would start a thread listing sources for some neat survival items that are on the market today. These all fit nicely in the hollow handle. Because items like fishing gear, needles, thread, etc. are readily available, I'm focusing on fire starting, compasses, and handle wrap.

FIRE STARTERS:
Ferro Rods - Fox Firesteel is a good size: http://goinggear.com/index.php?main_page=index&cPath=4
Survival Spark - Quality brass construction compliments the 18s brass hardware: http://www.tripleaughtdesign.com/Equipment/Tools/Survival-Spark
Spark Lite - Less expensive alternative to the Survival Spark: http://www.bestglide.com/Spark_Lite_Info.html
Fire Tabs - These work well as stuffing to prevent all items from rattling: http://www.bestglide.com/Tinder_Quik_Info.html
NATO Matches - Mini flares: http://www.bestglide.com/Lifeboat_Matches_Info.html
Stormproof Matches - More mini flares: http://www.rei.com/product/617046

COMPASSES:
NATO Compass - High quality dry compass, but expensive: http://www.bestglide.com/FB1605_Info.html
Compass capsules - Liquid filled compasses. The 14mm - Grade AA compass is the current Randall compass: http://www.suncompany.net/prodList.php?subCat=20
Aluminum compass - Dry compass. Not sure about the quality of these, but they have an old fashion look and come in two sizes. Read on another forum that they are accurate.: http://www.stanleylondon.com/smcomp.htm

HANDLE WRAP:
Nylon Cord - Small diameter nylon cord in 13 colors. Scroll down to Size "5": http://www.paragear.com/templates/parachutes.asp?group=33&level=2&parent=193

Needless to say, there are a lot more items out there, but this will give you a start especially those getting their first 18. Feel free to add to the list.