If you are a Mac user with a newer version of the Mac OS, you may already be familiar with the feature AirDrop. AirDrop allows you to quickly and wirelessly share files between your Macs on the same local network.
Here is a little Terminal trick to activate it on machines that do not support it by default. This will also allow you to share via ethernet, since normally, AirDrop is limited to Wi-Fi.
First, open up the Terminal application. (As always, practice Terminal commands with care.) Then, type the following commands:
defaults write com.apple.NetworkBrowser BrowseAllInterfaces -bool TRUE
Hit enter and on the next line type:
killall Finder
The killall command will restart the finder of your Mac. Once it relaunches, AirDrop will be activated.
If you ever want to disable this change, enter the same commands as above, and just change TRUE to FALSE. (Like this:)
defaults write com.apple.NetworkBrowser BrowseAllInterfaces -bool FALSE
killall Finder
Enjoy!