I've wanted a Network Area Storage device for a while but the prices seemed a little steep. I wanted one that could be expanded with USB ports to add my external hard disk, and perhaps a print server. Even the simplest ones seemed expensive.
Recently, just by chance, I found the Freecom FSG-3 Storage Gateway. It not only had a 400 GB capacity and have 4 USB2 ports, but it could also manage printers (a print server) - fantastic!
There was a wireless version available too but since I already had wireless router I decided against it.
I colleague at work mentioned he had the exact one I was looking to buy. After a long discussion I decided to buy one from Amazon. Three short days later, it arrived!
I plugged it in and connected my two desktop PCs and everything worked fine, no problems. Then I tried plugging my ADLS wireless router into it, via its WAN port. That's when I started having problems. The FSG-3 recognised that the router was plugged in but it simply didn't want to talk to it. None of the instructions that came with it mentioned anything about plugging routers into it, which I found strange as a lot of people these days have wireless routers, especially as some Internet providers give then away when new customers subscribe to them.
I tried changing various IP address configurations, switching off the DHCP on each device and even on both devices so all had fixed addresses (192.168.1.x) - nothing worked. Each worked by themselves but not together; the wireless router worked, connected to the Internet and allowed my laptop to gain access to the Internet via wireless link but, despite all the lights flashing, neither the desktop PC's could access the Internet (FSG talking the router) nor could the laptop access the FSG-3 (router talking to the FSG).
To make matters worse, my printer (HP Colour Laser 3500) wouldn't print through the FSG. Again, the FSG recognised the presence of the printer, but nothing would print. I should point out that you are advised to install some software to access the FSG easily. I didn't mind the printer not working too much as I don't use it very often and I could plug it into one of the PCs and share it as before.
Another, more serious issue was my external hard disk suddenly became Read Only! I suspect this was because the FSG was using Linux and the external hard disk was using NTFS. I could access it through the FSG but the only way to write or delete files was to unplug it and re-plug it into a PC.
One of the nice aspects I found was that Freecom set up a special wiki web-site (www.openfsg.com). In here I found that a beta version of their latest firmware was available (3.3.13), including a detailed description of the changes made since the previous version. This version included enhanced features for connecting to the WAN (i.e. routers). I downloaded it and upgraded it into the FSG. The FSG interface now included a Basic Setup feature (in the Connections section), which allowed the FSG to be a 'switch'. I changed the IP Address, Gateway & DNS Server to match the wireless router and suddenly I could access the Internet through the FSG - it worked! Amazing!

On the plus side, it is small, light, and very simple to use on a day-to-day usage. There are two USB ports at the front and two at the back, so USB devices that you use all the time (printers, external hard disks) can be connected at the back, while USB flash drives and other devices that you use now and again can be connected at the front, similar to a standard PC.
It has a MySQL (database) server, web server, FTP server and file server that allows selected users and groups to access root folders you want them to have. (Note: the beta firmware allows the folders to be read-only depending on the user, which is helpful). It also has a media server; though I don't use it so I can't really comment on it (do you really need it?).
The wiki website has a forum where you can find or ask for useful advice.