Windows/Mac/Linux (All platforms): FilePhile is a peer-to-peer, multi-platform app for getting files of unlimited size between yourself and anyone else willing to give it a try.
After registering at FilePhile's site with an email address and password, you grab and install a copy of the Java-based app, launch it, and add email addresses to your buddy list. Sending a file is a simple right-click on someone's name, but you can limit the bandwidth eaten up by FilePhile in its preferences. The transfers themselves are encrypted, and, as the site boasts, can be any size. That's about it, but that's probably all you need.
FilePhile is a free download for Windows, Mac, and Linux systems. It requires a Java platform version 1.5 or later to run.
