Okay, if they are into food/keeping healthy;
A vegetable steamer, get a 3 tiered one, they are the business. (in a foody sort of way).
If your getting a coffee machine don't get a high falutin one that is high maintenance, get quality but simple.
A subscription to Sky sports/Setanta. (Or one of those boxes that are not illegal to have but illegal to use ;-)
A honda petrol lawnmower, they are the biz if they have a big garden.
Insulation for the attic ( a practical present for people with poor er....insulation)
A voucher for a really romantic restaurant ( you can tell them that now they are living together they'll need all the help they can get!!)
A share in a greyhound.
Personally I'd go for the steamer (electric!!) but hopefully 1 of the suggestions will help!
Colm