YouBackItUp is a great way to share large files with friends. YouBackItUp has employed a really neat drag-and-drop interface that makes it dead simple for anyone (read nontech-savvy people) to use. Instead of hitting a browse button and fishing through your hard drive to find the file, you can just drag the original right onto the interface, and it takes care of the rest. When you're done uploading things, you're given a simple URL to send to friends or family where they can download the files.
What makes the service a real winner in my book is its generous storage size and bandwidth, which has no limit besides a 200MB cap per file. This means you can have several gigabytes of stored files as long as they're within the limits. The one caveat is that the files will be removed from the service if they sit dormant for 20 days.