We are currently using a local ISP to host a FTP site for exchanging graphics files with our partners. In total there are around 30 accounts with approximately 17GB of files.
I've been trying to find an alternative hosting solution, but it seems like I'm asking for something impossible within the realm of shared hosting. One particular host told me that despite their plans offer unlimited space, bandwidth and FTP accounts, doing so is in direct violation of their ToS.
Aside from purchasing a dedicated server or VPS, what options can you recommend for hosting a FTP site?
UPDATE: The prospect of using Amazon S3 sounds great, but products like Jungle Disk are probably out as it would require re-training all of our external partners. Is there any way to setup a pseudo-FTP server that stores the actual files in the cloud?