I think some homebrew emulators have the option, and obviously XBMC will load videos over just about every network protocol going. Commercial games are right out though.
After that you are going to have to turn your network storage into a SAN and somehow chain enough things that it presents the connection as not SAS or one of the big boy protocols but IDE (or in the case of soft mods IDE that the xbox recognises). On the less ridiculous end of the scale ($10000 is entry level SAN if you are lucky) I could see some kind of NAS setup that does network and internal drive, and it working on the xbox (we have things like media hard drives that have USB and media out, or indeed your phone if it was made at all recently can probably be on USB and doing all it does at the same time). In reality though just get a decent size hard drive.