Pretty much every current mid-high end amp will have your essential requirements and some of your 'nice to haves' like multi-room and ipod dock compatibility. There are new amps coming from Denon, Pioneer and Sony all due out soon. The Denon 2809 might interest you but lacks some of your nice to haves. DAB is pretty much non existant on receivers, so a separate tuner is probably the way to go. Networking is really only found higher up the price range but streaming video isn't possible, they can do internet radio and streaming mp3 etc. (usually via windows media). I personally would prefer a separate streaming solution e.g. squeezebox so I didn't have to squint at the amp's display or view album art and so on on a web based device or remote. If you have a PS3, Xbox 360 or similar video streamer that take care of that for you.
High end Onkyos e.g. 905, Yamaha 3800, Denon 3808, Pioneer LX70 all have networking (no DAB
AFAIK) and all cost around £1000 and upwards give or take (shop around for deals).