Not in terms of what you pack - but how you pack it!

I swear by
* zip-up packing cubes
* buying toiletries in small sizes as I go
* a million ziplock baggies
* a backpack that opens both on top and in the front
* rolling stuff up (instead of folding it)
* travel towels (terry cloth is soooo heavy and big!)

Now you - share yours!

When I seen this thread I thought "yes I'll say roll your clothes up!" but you did that first. Heh. ^_^
Putting solid objects in shoes.
Sharing the weight amongst all the suitcases (this is what my parents did between the three suitcases when we went on family trips)
Not taking five different hairdryers on an all girls trip.
Putting items you're likely to need first at the top.
As for travel towels I find they're not as absorbent as normal towels so buy a big size (unlike me when I went to Peru -_-)

Many of mine are repeats of what you two have said - great minds think alike!
-Ziplocks of all sizes plus extras
-Those fancy compression space saver ziplock like bags
-Compression backpacking bags (full, they act as a travel pillow)
-Solid shampoo,conditioner,lotion,laundry detergent inside a small tin stuffed inside a shoe
-Sample sizes of whatever in my purse
-Since I usually travel with my husband we get TWO TSA-approved quart bags... meaning: One is for sunscreen, bug juice and his requirement of liquid body soap, and one is for our pre-purchased mini bottles of booze. What?
-Backpack that will fit in overhead - no checking luggage for me! And yes, it must be accessible from top AND from the front - this changed my life!
-Tiny compressible daypack for picnicking so I don't have to lug grocery bags at destination
-I've always been a roller of clothes, but I am quite interested in trying the bundling method
-I wear the bulkiest items on travel days
-I put everything I'll want for the plane on the top removable compartment of backpack and it's mostly food. Most of this gets eaten before we get to the destination, so I'm already lightening my load
-Travel towel OR cotton dupatta or sarong. They all serve the same functions, but the dupatta and sarong dry a lot quicker!
-Makeup samples! In a tiny "snack size" ziplock I fit more makeup than I ever use. Mary Kay has awesome ones like three eyeshadows on one cardboard, and mini eyeliners and foundations and whatnot (ten years ago I thought I'd try to sell Mary-Kay but spent most of my time/$ buying sample products that I am still using up hehe)

I usually roll up clothes then put them in the compression backpacking bags so there's this little dense category (ex: cold weather outfits, warm weather outfits OR bottoms, tops/dresses)
It's heavy, but leaves my pack small enough to fit overhead, and gives me extra room to take things home with me.

Granted, these are for trips three weeks or fewer, though I imagine my method will work for longer trips if I leave the hubby at home!

I agree with rolling the clothes, getting a front opening backpack and taking solid shampoo/conditioner etc.
Also, I always take this huge pink sarong with me, it's great for a bedsheet or blanket if the bedding in the hostel is icky, sleeping under on a bus, towel, post shower cover-up picnic blanket, scarf/shawl, turban, sarong...it is multi use and takes up such a small amout of space. I usually also take a padlock. My mum makes me take a door wedge, becuase she belives a door wedge placed in a closed door will make it impossible for the door to be opened from the outside, thus protecting me! I've never had to see if that works. My friend always brings a string of tiny little bells, which we tie around our backpacks if we're on a bus or waiting at a station, that way if we accidentally fall asleep and someone moves our stuff, the bells with alert us and our stuff won't be stolen!

If I'm going somewhere cold and taking a jacket/coat, I pack my clothes INTO my coat/jacket, and zip it up. Arrive at destination, take out bundle, and VOILA! No more searching for that one tshirt that you swear you packed That can work for some backpacks but mostly suitcases.

My packing tip is to NOT pack efficiently. The more stuff I can fit in my bag, the more stuff I take.

Also, packing my case then walking up and down stairs about 10 times -- then repacking!

I like to not just roll clothes but roll entire outfits in the same bundle. It saves scramblng through my bags and keeps everything tidy for just a little longer! I also have one of those luggages where the top unzips into a separate compartment. I keep all my travel essentials (daily toiletries/PJs/hairdryers, phone + camera chargers...etc) in there for easy access.