I've noticed a trend on the net to give "unlimited" of some kind of service. Whether its it's bandwidth for internet hosting, space for file storage, email storage, etc, there tends is always a catch. Lets be real, its impossible to have unlimited resources, every computer has its limits.

A year or two I signed up for internet hosting from BlueHost (the same company known as HostMonster). Now, overall I've been very happy with bluehost and find the price to be a great value for what you get. At the same time, I'm disappointed that when I signed up I originally had something like 500gb of file storage avaialble (way more than I'd ever use) but since then all accounts have been changed to "Unlimited" file storage. Of course this is a ridiculous claim that everyone can store unlimited amounts of data on the Bluehost servers or they would quickly run out of space. So then how do they keep account holders from uploading data? Its called a rigourous TOS and most likely a bit of disk usage analysis (for you unix/linux users, that would be du -hs /home/$USER). The TOS states the content stored must be for web hosting and not for backup purposes.
Now if I were to offer "unlimited" storage space to customers I would be sure to include the same provisions in my TOS, however, I think the idea of unlimited is a silly marketing ploy these hosting services use to say "we are better than they are, we give you unlimited storage".
In reality though, if a company offered me say 20GB of storage which I could store my websites and web data, and whatever other data I wanted to store (assuming its legal), I'd respect the company for it much more than these "unlimited" everything companies like bluehost.

At one point I was using bluehost to backup my photo collection (which I could easily say was for a photo gallery software I actually did have installed) which includes about 5gb of photos. Many hosting services similar to bluehost allow storage of 100GB or so, and I was only about 7gb of data total on the server. However, one night my site's were responding incredibly slow. So I logged into CPANEL admin account to checkout the site utilization. Disk usage was at 99% at the time and obviously causing major file system slowdowns. I took a look on the forums to see if anyone was complaining about it, but instead I found a post of someone who had recently had his account shut down because he was using bluehost for personal backup along with web hosting. The user said he was only storing 15gb or so of data, which who knows whether or not its true, but bluehost just plain disconnected his websites and gave him something like 24 hours to pull his data from the servers. No warnings, no slap on the wrist, no notice, nothing.

After reading this I quickly removed my 5gb of photos that made up like 80% or so of the space I was using. I checked disk usage afterwards and It appeared that I had actually droppped the overall disk usage by less than 2% which means they probably had less than 1TB of storage on the server.
By the next day the straightened things out and EIther added more storage or deleted some acounts, either way they got the server back up and responding quickly, which I am happy for.

Anyways, long story short, don't believe the "unlimited" b.s. Bluehost is a good host to have overall but if you can find a host with the same features (SSH access, php5, mysql5, cron, etc) but with limited storage and bandwidth, give them a try.
It would be great to be able to do offsite backups affordably. I guess its just too much to ask for from a company charging $6/month. But if you're only using 10gb or so, whats the big deal..