Well for craftable items, including food, if you set up a home business, even if you always keep it closed, any items that anyone in the household makes will automatically go into the inventory of the sim who made the call to start the business. It doesn't help for items already in inventory that you need to switch, but it's good to know for future reference.
I have a servo who bakes pies and cakes at home so her owner can take them down to his store and restock. Rather than me transfer them all by hand, I had the owner call and set up a home business, put up a sign, kept it closed and now all the pies and cakes she makes go straight into his inventory.
I agree though that there really need to be a program, hack, or something to mass tranfer items from one sims inventory to another. I also think when a sim dies all their inventory items should transfer to a relative or on the lot. Apparently in TS2 you
can take it with you.