Dropbox creates a folder on your PC and can be used to
- sync files across several machines
- access your files via the website
- storage for back up files
- share large files to other people
- set up shared access for several people to a folder or files
- host image galleries
- compatible with Truecrypt containers etc.
- all files remain on your PC/s as well of course
- it actually works, unlike many of these things
2gb storage is free.
If you register using my personal link, below, I get more free space and so do you (above the usual 2gb)