does anyone know of a way to transfer files to someone else's computer from your own withOUT using a router/network/etc.? i.e. just connecting a line between the two computers, kind of like you're using one of them as an external storage hard drive? please help

If you connect whatever the mean 2 computers you HAVE a network. Now, if both are macs, it's easy to connect them using the filesharing system.

-Just use an ethernet cable and go. (macs less than 5 years old don't care if the cable is crossed or not).

In the system preferences:
- check the relevant firewall ports (sharing/firewall)
- check the relevant service
(both should open be checked automatically when you check the other.
- Assign static IP in the network configuration like 192.168.0.x, one for each computer.

In the finder, menu "Go", "connect to server, enter the other mac IP with "afp://" before the number, log on using the login/pw of the user on the other computer.

And it should work

Note, create a custom network configuration for this, not to loose you internet config of course…