Everyone: Talk about a way that you think an already-existing thing could be improved.
Everyone: Discuss them!
Doesn't matter how big or small the change is, or how common or uncommon the thing is.
My random thought for now: Thermoses/coffee-cups should have some sort of hotness gauge, so you know when to drink your coffee. I always either drink it too early and destroy my tongue, or too late and have to chug down lukewarm coffee.
Another random thought: Soda companies should market soda bottles that are half-n-half (for example: half coke half sprite). The sodas would be separated into different halves of the bottle, and you could choose which comes out.