(Melting ice.)
Other types of necessities (in conjunction with putting frozen liquids and warm areas): child, oneg Shabbos, etc.
working with items that are made to go in and out on a constant basis;
A few more thoughts on grapefruit, squeezing baked or cooked Apple.
Folding Laundry That Might Get Ruined if I Keep It Like That Over Shabbos;