I would like to run a maintenance-free NAS on a linux distro that is stable and reliable for uptime and can be run monitor-less for the most part with random SSHing into the terminal from my mac laptop.

It's a basic home-built miniITX (AMD kabini) NAS that will just have two SATA drives that use a BASH script and cron job to copy files from one to the other on a nightly basis.

Another requirement would be easy network share access from windows/mac OS devices on the network or iPhone apps that can connect to network shares for backup.

I use a mac at work with moderate unix command line usage and SSH interaction with our DV web servers so I don't mind something that isn't "I just got here from windows" friendly but having an easy GUI is always nice.

None.  BSD is the proper OS for storage.

Edit:  Unless you want to run Ceph

I run Slackware, got several machines using it.  One has been up now for over a year without reboot.
Others I've had to reboot for various reasons,  but never due to instability.  I've never had any of these machines go down by themselves or become corrupt in the last 10-15 years except for a couple of hardware failures.

Before I recently switched over to Synology I had a NAS for three years simply using Ubuntu server. Worked well for my needs.

I had Netatalk set up for Mac Time Machine-style backups. pyTivo was set up to transcode video to my Tivo. Other than that I had basic file sharing in place. My requirements were pretty low but overall it was trouble free and performed great. There was no GUI on this set up and once in place all maintenance was through SSH.

FreeNAS worked pretty good last time I played with it.

You asshole.  I saw the thread title, clicked on it thinking, I'm going to go into this thread and post "FreeBSD", and never come back to it.

And then I read the first post as it opened.

Not only is BSD a real man's OS, ZFS is also the shit.

I know. All the good ones are.

I know there are NAS-specific builds such as NAS4free and OpenMediaVault

Since i'm not running RAID or anything and just doing a basic rsync and file share from the DMZ on my network- do I really need the features of 'NAS-specific' builds?

Do you give zero fucks about the data?

unraid

http://lime-technology.com/

two servers running here, one for over four years, have seen uptimes as long as six months, and that's on crappy consumer grade hardware.  go to the forums and see what server class stuff guys are using (supermicro etc) and expect even better stability.  stupid easy to configure, stupid easy to maintain, hard disks can be different sizes and you can upgrade them one at a time on the fly whenever.  many will note that its not "true raid" but for a NAS it works amazingly well, and i have done a few disk rebuilds (mostly in testing but once for real on real data) and have never had a problem.  purists will preach freenas, which is awesome, but my largest unraid array is coming up on 60tb, and i can't afford 60gb of ram for it (last i checked freenas wants 1gb ram per 1tb disk space, others will correct me if i'm wrong here).

had a six-disk system running on a 1ghz dualcore amd with 1gb ram and got 40-50mbps read/write, with old slow disks, my better hardware is considerably faster and more capable (especially on writes with a cache disk, some guys are even using ssds).  disks spin down when not in use, all my systems sip power (you have the option of keeping them all spinning so you don't have to wait for spin-up when accessing data).  

the v6 can do virtual machine stuff and other modern whiz-bang things, although i'm not using it for that.  i have on running v5 and one running v6, will likely upgrade the v5 machine to v6 in the next few weeks, both versions run great.

Because I may want to run other processes or apps such as an iphone app compatible network share or custom home network share settings?

or maybe I'm misunderstanding how much freedom the nas builds give you...

The NAS-specific builds are the way to go if you don't have any specific requirements that it doesn't support. The only reason I rolled my own 5 years ago was because there was no pyTivo option with FreeNAS. Checking recently shows it is now supported. If I had to do it all over again that would be my route.

What kind of share does the iPhone need to access? Isn't it just CIFS, AFP, or something similar? My Android devices connect to typical CIFS/SMB shares that FreeNAS would easily provide.

AAR:

Setup the new box and it's working great. Specs:

AMD Sempron 3850
MSI AM1I
2GB DDR3-1600
Silverstone SG13
EVGA 430w
+ Two SATA 2.5" HDD's I had laying around

Installed OpenMediaVault through UNETBOOTIN on a Sandisk Fit 32GB drive which is running on the USB3.0 port and so far so good...I setup a basic RSYNC cron through OMV to run every 23 hours that copies files from share drive 'X' to drive 'Y'.

Hopefully this will last for awhile.

OMV was super easy to install and the login GUI is also very easy to learn. If anyone needs a good DIY guide here is one from another guy who did very detailed instructions:

http://en.jose-crispim.pt/artigos/armazenamento/armaz_art/06_openmediavault.html

Yeah. Try OpenBSD. It's the most secured BSD of them all.