I tried to find out the best method for a storage system and I found FreeNAS.
Based on FreeBSD it only needs 128MB of free space for the OS and comes with full support for CIFS (samba), FTP, NFS, TFTP, AFP, RSYNC, Unison, iSCSI (initiator and target) and UPnP, software RAID (0,1,5), ZFS, disk encryption, S.M.A.R.T/email monitoring with a WEB configuration interface. So almost anything you need for a decent NAS server.
Everything is done through it's web interface, including stuff regarding to services, users or monitoring. The bonus is that you're not locked out, you can always go and login as root if you don't like it's web interface/list menu from the console.
I've installed with FTP over SSL on two disks of 1TB that synchronize each other using rsync every hour. I wanted to skip software RAID because it can make your life miserable and used a basic PC so no hardware RAID.
I can say I've installed it installed so fast from a Live CD that I double checked that it really has everything working without the CD. Bad part is it got a little tricky in handling partitions and mount points through the web interface. Took some minutes to figure it out.
I think it's missing upload through the web interface at the moment. But everything else works great. It can even say "hello, I'm here" through Apple's Bonjour, beating their Time Capsule's only advantage. And FreeNAS even got to version 0.7.1 :)
So there you go:
It would be for the best to check out the Hardware Compatibility List (nice thing they have one) before buying any hardware:
Enjoy your new tons of storage!