A greenhouse! Just kidding, I know that you already ruled that one out
I have a lot of building needs right now, and also some crazy ideas, and so if I had the lumber, currently it might go towards:
-deck building
-animal shelter/barn buildings, chicken coop
-solar panel racking
-lean-to roofs
-firewood shed
-fencing/gates
-hunting blind/raised platform for hanging out
-outdoor kitchen
-animal feeders
-raised beds/part of greenhouse structure
-bolt some together to make strong beams
-trade for other materials/things I need
-sauna/hot tub/wash house
-cold storage/aging room/root cellar
-skiddable structures...
-solar water heating, solar oven
I also wouldn't hesitate to store the lumber properly and have it on hand for when it is truly needed.