For the longest time I assumed that when uploading CRM customizations it only took a .xml file.
It never occurred to me that when I export customizations the .zip file it gives to me can be uploaded too! I always assumed that I could only upload the xml file.
Yes you don't need to extract the xml file from the zip to import the customizations, you can feed it the customization xml file in a zip file.
It seems that I was not alone in this assumption as a number of people who I have shown this to have had an ah ha momemt. ;)
This is a simple trick, but good a one.