Jonathan
Castle Inn Talgarth, does B&B, 3 rooms from memory and three bunk houses too!
Also saw this on Saturday Kitchen thingy once, looks great for your deep pockets
http://www.skenfrith.co.uk/ - Bell at Skenfrith - on one of the best roads in the area. Gastropub with rooms andriverside location
In the town, there are 2 B&Bs on/near Hereford Road: The Guest Houseand
As stated above, Talybont is a nice village with a couple of pubs. Another nice place is Crickhowell - visit the chocolatier. The Bear Hotel is nice but you are spoilt for choice in what is a lovely village. See here