Planet Hiker
The following packing list is fine tuned for travels in Central & South Americas, as well as South East Asia. Note that in South East Asia it is much more difficult to find camping sites. Thus, consider skipping the trekking gear unless you are specifically going there to trek.

Check out 5 Best Countries to Backpack!
Clothing
Sox x3 pairs
Small towel
Surfing shorts
Short sleeve shirt (x3)
Long sleeve shirt (x2)
Underwear x5
Light hat
Handkerchief x2
Rain jacket (Marmot waterproof breathable)
Sandals (Teva)
Fleece jacket

Trekking Specific Wear
Tights
Beanie
Turtleneck
Boots (Asolo, FSN 95 GTX - if jungle trekking, consider military Jungle Boots instead)

Trekking & Camping Equipment
Kelty Red Cloud 5400 Backpack
Sleeping bag (30C)
Tent (Coleman Peak 1 Cobra)
Sleeping mat
Stove (MSR Dragonfly)
Fuel Canister (MRS)
Utility Clips (x2)
Spork (Nowpeak, titanium)
Aluminum pot (2.5 cups, +lid)
Detachable aluminum pot handle
Lighter
Water filtration bottle
Plastic cup
Biodegradable toilet paper
Headlamp flashlight
100ft rope
Purell 10oz
Knife
Electric heating element for warming water - when staying in hotels

Emergency
Compass
Flash light
Sawing kit
Waterproof matches
Whistle
Windproof lighter
Zip ties
Rubber bands

Medical
Bandages
Ciprofloxacin HCL (500mg x12 antibiotic for diaria)
Chloroquine (500mg x25 malaria preventative. Note: purchase abroad)
AllClean eye drops
Neosporin 1 oz
Rubbing alcohol 5oz

Photography
Camera (Nikon N80)
Wide angle lens (Nikon 18-35)
Telephoto lens (Sigma 28-200)
Graduated filter (Cokin)
UV filter (Hoya)
Tripod (modified Velbon Maxi)
Camera Bag (modified Lowepro)
Slide film (Velvia)

Toiletry
Deodorant
Toothbrush
Toothpaste 10oz
Floss
Sunscreen 10oz
Insect repellant (30% DEET)
Small scissors
Chopstick (Carmex 10g)

Other items
Daypack
Mosquito net
Notebook
Pen x2
Inflatable pillow
Sunglasses
Waist pouch
2nd wallet
Dictionary
Passport
Photo copy of the passport
International Driver's License
Immunization certificate
Printed list of phone numbers and addresses
Utility clips x2
Ziplock bags x3