I know it's not much, but a free beer, snack (small sandwich and a biscuit you get on LH) and a coffee makes people think they're getting better value. People seemed to like the whole Diamond service. Bit of a dated name, but why not bring it back? They've went back to "British Midland (international)" - so why not bring it back.
I agree something for free would be good in an ideal world- but some of the buy-on-board prices are actually quite affordable when compared with competitors on the routes BOB is offered.