Around my canteen, either a Nalgene 1L bottle or a Gatorade 1 qt bottle, I place a Snowpeak 700 (cc) cup/pot. It fits quite snugly, with just enough space to accommodate a windscreen. I can heat/sterilize all the water I need and cook all my meals in this container. For once, this is a valid use for titanium.
You can also fit a 110g fuel canister, gas stove, mini-bic lighter and a small pack towel inside one and still close the lid. Or an alcohol stove, wind screen, lighter, folding spork and small towel. One of my favorite bits of gear, I have several.