Chris (Whites11) and several others have pointed that the source code for a device similar to Agestar have been released by a German company (http://www.multicase.de/en/products/76/ns348s.html). I have not looked carefully at the source code of this one, but none of the people on the mailing list have got it working with networking enabled.
Kari Ahtiala who owned several NAS devices (SLUG, NCB3AST, NCH3AHT), said that you can just move your disk from NSLU (SLUG) to Agestar just fine:
after upgrading the firmware, boot the Agestar without the disk, ssh to it, plug in the disk, mount it and chroot to it, and then mount -t proc /proc proc, and everything works as if the Agestar had been booted off the hard drive.
This is fine if you want to just borrow the disk for testing or cloning purposes. To convert it to be used on the Agestar exclusively, I copied /etc to /etc-slug (so I can revert by "mv etc etc-agestar" and "mv etc-slug etc" and enited fstab, network/interfaces and modules and issued the command "e2label /dev/sdb1 /" as you instructed.
And here are some tips from him:
I pretty much cloned my SLUG so the Agestar is now a NFS and Samba server, Web server and X server. The Xfce4 applications are usable on the Agestar – Mousepad is an OK editor and Thunar is OK for a file manager (these have a habit of Segfaulting, though, but at least X works: xterm, kpat, xpat2 and spider!). Using "ssh -CY" instead of "ssh -X" doesn’t seem to make much difference.
Usbmount is very useful: plug in a USB drive and it is accessible on your local network if you share /media via samba. Just edit /etc/usbmount/usbmount.conf: the default filesystems are ext2 and ext3 but you can add vfat and ntfs but you need to add some options:
To get read-write on an NTFS drive, you need to cheat a bit: first install ntfs-3g and then
ln -s /usr/bin/ntfs-3g /sbin/mount.ntfs (this is because ntfs-3g is a program and the old ntfs is a module).
A tip from me is that if you have a problem with your Agestar, just search google for your problem, and add "NSLU" "debian" (or NSLU2 debian). The solution for debian NSLU2 should apply to Agestar with Debian.