I am looking for something that does the same thing as Airdrop that would work on Windows/Mac/Linux. Because of hardware it would most likely have to be LAN-based, but I am perfectly fine with that. Anyone know of such a program? Thanks :)
Have a look at Transfer on Lan - it's not as full of hardware encrypted, peer to peer mesh network goodness as AirDrop, but it's the closest stand in for AirDrop that I've seen in a cross-platform client.
It uses a normal network as opposed to building up a secure temporary network, but other than needing java, it's pretty easy to implement.
Though it's a bit different of an approach, Dropbox is an excellent solution to this problem.
If the computers you're moving data between are next to each other, you might like Share Mouse. Share Mouse actually let's you drag and drop files and folders between computers as if the other computer were just a secondary display.
I'm using it personally because I have my MacBook next to a Windows computer and the drag and drop functionality comes in handy multiple times a day. There's also clipboard sharing support.
You can also use FileDropMe which is an app that works similar to AirDrop across several platforms (including smartphones).