I recently ordered myself a bargain NAS enclosure for a SATA hard disk. You fit your Hard Disk (not supplied!) inside, plug it into the power and the network, and you have storage available on your network 24/7.
It's got an SMB client (so it works with Wondows), uPNP, FTP and even a bittorrent built it.
And it was under £13 new from eBay!
http://r.ebay.com/9hKGN3It arrived today. So far seems very good.
Cheapest I could find an equivalent product was around the £40 mark (though happy to be proved wrong if you know better).
3 points to bear in mind :
o There's no hard disk, you provide your own. What do you expect for £13?
o It's only 10/100. Doesn't do gigabit ethernet.
o The supplied PSU has a European plug on it (this is pointed out in the eBay listing). You won't be able to fit a UK plug to it as it's a moulded PSU unit with Euro plug built in, but you could plug it into an adaptor, or find another 12v 2amp PSU (as I did)
Curiously, the box is 95% German, the manufacturer is German, the PSU is evidently for German market but the instruction leaflet is in English!
So far it's working well, will update if I find any problems.
Ian