NDBs are cheap and useful. I use Henton frequently for routeing to the west of Luton, in order to avoid Dunstable and Halton, which is becoming increasingly active. We atDenham also have Chilton on our doorstep, also very useful as it marks (approximately) the northern boundary of the Heathrow Zone.
When we bought our PA28 (seriously 2nd hand) it lacked an ADF so we fitted one, mostly for our IMC rating work but also because we recognised its usefulness, despite all the well-known deficiencies of the system. OK OK you can't use them at night, on the coast, when there are thunderstorms about and you have to work out for yourself what radial you're on, no distance info etc etc. Apart from that!!!
Cheers,
The Odd One