Any DVR with a USB port can do this in theory.

I have a Topfield TF5800PVR connected to an unSlung Linksys NSLU2 with the Topfield FTP daemon running (tftp-topfield from meory). This allows streaming video to any PC on my network running VLC.

More info from the illustrious www.toppy.org.uk

see title

Pretty much any cheap PC with a freeview tuner card and MythTV.

The Topfield TF5800PVR + slug (or one of the alternatives) is superb* as both a normal under the telly PVR, plus having it's hard disk available via FTP using the slug.

*That's superb if you patch the hell out of it and then add TAPs to make it do exactly what you want. It's a bit grim out of the box but it has been transformed by the multitudes of clever people at toppy.org.uk.

The old Netgem (also badged by BT for a while) freeview boxes support some wireless and wired adaptors via a USB port, but they're not DVRs and don't have a hard disk either. Not a bad device for it's time and probably still thousands of them around.

Can be bought with DTT, Sat or cable tuner. All models networkable, can record to network share on PC, Mac or NAS. Pricier models can have internal drive or use CF card, can also be fitted with two tuner. They're also linux boxes and fun to play with.