Bedding, pillows, towels, etc.. I use those vacuum bags. Load them, zip them up, and suck the air out of them. It shrinks them down pretty well for easier storage in a lot less space. I could probably leave them that way on the boat for the winter, but I like to bring it all home for a good airing and washing in the off season. If you were tight for space at home you could get away with storing them on the boat this way. I bought the vacuum storage bags at Wal Mart.
I also bring all the cushions home for a good airing and storage. Non perishible hard items (dishes, cups, etc.) stay aboard, then come home in the spring for a run through the dishwasher.