You should only do this if you are on a LAN behind or with a firewall.
There are many ways to share files between computers. This howto will show you how to setup a folder on Windows 7 so that a Linux computer on the same LAN can access it with no password. This share can be accessed form other Windows computers too but I am unsure about Mac.
Setting up Windows 7:
Right-click on the folder you want to share and click on "Properties". Click on the "Sharing" tab and then on "Share..."
Add "Everyone" and then make sure it has Read/Write permissions like Homegroup does in the picture below:

Make sure "Share this folder" is ticked and then enter your share name. I called mine EliteShare.
Tick the "Full Control" box.


Search for "advanced sharing".
Click the drop-down arrow for your current network profile. Most likely it will be the one in the picture below:
Select "Turn off password protected sharing" and then click "Save changes"
Accessing from Linux:
To access the share on Linux simply open Nautilus and press Ctrl+L and then type in:
smb://ipaddress/sharename/
Here is an example:
smb://192.168.1.100/eliteshare/
Then press enter and start sharing!