Saving money while traveling Part 2 - Packing Light

Some people love to over pack their suitcases while traveling.  But lets look at simplifying that and packing light!  What are some of the benefits of traveling, specifically packing with just one bag?  How about security because it never leaves your side and isn't checked; economy because you can hull it around without paying someone else or getting one of those funny carts; flexibility because you can go places a lot easier with just one bag than with 2 or 3 (or more!), energy because lets face it, 1 bag is a lot easier to carry than 2 or 3 physically; and peace of mind because you wont be paranoid making sure no one is stealing or pick pocketing your other bags; and finally, ecology, less stuff = less materials needed to produce = less energy needed to produce = less machinery = less fuel = less greenhouse gasses.

So now that I've hopefully convinced you pack with only one bag (preferably carry-on), let figure out a way to make this happy and what type of restrictions you'll have.

Restrictions:

• Size: most airline companies restrict you to only 45 linear inches in combined length, width, and height.  This usually equates to 22" x 14" x 9" or about 1.6 ft³. This is not much space if you think about it but we can still fit enough stuff in there for at least a week if packed properly.
• Weight: Many companies have a weight restriction of 40 pounds but some as little as 25 lbs.  Luckily for me, and you, they frequently don't weight them.  

What you need to bring:
Obviously this isn't the universal list that you'll use for every trip on every occasion, but there are some suggestions/reasons on things to bring with you.

• SIM card based cell phone - Acts as a watch, alarm clock, cell phone, calculator, flashlight in a pinch, & music player (if it's allowed.  Not to mention, if it uses a SIM card, it's usable in most of the world and you wont have to rent a cell phone!
• 3 or 4 pairs of undergarments & non-cotton socks (cotton is known for being horrible and completely useless if wet and do feet sweat? Yes they do.  So if you're planning lots of walking on your next trip, you might want to reconsider.
• Safety Razor - Safety razors are the best way to go, the blades are incredibly inexpensive, require no electricity, minimal maintenance, and once you're good, can provide a very close and smooth shave with little effort and time.
• Day Bag - to hold you stuff with while you're on the go around town.
• Digital Camera - Waterproof camera's now are becoming more popular.  Those are the ones that I'd really recommend you don't need to worry if you spill something on it, the weather around you, swimming, etc.  Not to mention, they usually handle sand & dirt better.

What are some things that you always pack with you when traveling?  How have you saved money while traveling?