I've assembled an annotated list of sites that offer free Internet file space. At this writing there are just over a dozen sites listed. These links will be updated periodically.
Some also focus on providing an easy way to make files available to others. With these services you can make some of your space accessible to others. This provides a great improvement over using email to send large files.
Most of the services require only a recent version browser, but some require you to download software that is specific to either Windows or Macintosh. Most of those that don't require a download work with Windows Mac, Linux or any other operating system.
All of these services seem to be useful, but the question of security inevitably comes up when trusting someone else with your data. All of the services use password security and a few also use SSL (Web encryption). SSL is not used on many of the services since it slows down file transfers. Even with the best security I wouldn't store top secret files with any third party. Of course, since most of my files are not of a sensitive nature, I would not hesitate to use any of these services for most purposes.