Accio: To fetch car keys, identity cards , homework etc without a search operation.
Confundo: To use on teachers, customers etc when homework is not done, deliverables are not ready etc.
Expelliarmus: To use against opposition before any negotiation.
Homonem Revelio: To use at the USCIS, in banks etc to find out if there is at least one human being left at the counters
Locomotor: Obviously, to get heavy furniture and book bags of children up the stairs.
Muffliato: To discuss proposals, finances etc in crowded cafes, can also be used to have full blown quarrel in public.
Obliviate: To forget.. When things are really bad. [ Seems better than substance abuse]
Riddikkulus: To see monster-under-the- bed, the angry boss and snooty in laws , for what they really are.
Sliencio: To use on the loud cell phone user in the next seat.
And of course,
The Room of Requirement: To find bathrooms instantly when traveling with small children.