Going through the list of National Rail Bus Links, the National Rail ticketed destinations (with routes and railheads) I can identify are:
Abingdon (Oxford Bus company X3/X13 via Oxford, Thames Travel X2, via Didcot)
Blandford (morebus X8 via Poole)
Callington (Plymouth Citybus 12 via Plymouth)
Hadrian's Wall (Go North East AD122 via Haltwhistle or Hexham)
Hythe (Waterside) (Bluestar 9 via Southampton Central)
Launceston (Plymouth Citybus 12 via Plymouth)
Swanage (morebus 50 via Bournemouth)
Ventnor (Southern Vectis 3 via Shanklin)
Wallingford (Thames Travel X2 via Didcot or X38/39/40 via Reading)
Wantage (Thames Travel X32 via Didcot)
I'm leaving out area and LA ticketing (e.g. Tyne & Wear area tickets), or any ticket analogous to PlusBus (GTR keyGo, for instance).
For you, that Hadrian's Wall ticket is £12.50 at the moment, so same price, and presumable same validity, as the
AD122 Adult Day Rover, which is valid for a day's travel on the AD122 (a tourist service which is excluded from the North East Explorer, £10.50)