Here are a few of the best-featured free services:
- DivShare: Has a limit on the size of files, but has no limit on disk usage. Their blog reveals they have been in operation since late 2006 and have just past the TeraByte storage mark--i.e. they are really still a small operation.
- FileHO: No limits on file sizes or diskusage, and no limit on time. Some interesting comments here. Sounds too good to be true. Provides FTP services as well as web interfaces. Not much other information about the company.
- in.solit.us: Damned by its blog. They reveal that they were shut down temporarily in early 2007 by their host, Dreamhost, for violating terms of usage--probably for sharing illegal files. Overall, they look very amateurish.
Usually, you get what you pay for, so my guess is that if your files really must be preserved, you should pay for this service. Amazon S3 is the most famous of these, with fees of $0.15/GB/month for storage and $0.20/GB of data transferred. Several smaller companies attempt to provide higher level services on top of S3.