Leave food unless we're asked to take it home again - and when we have people over, we generally suggest they take anything back with them cos we either won't eat it or we have over catered and have other left overs to deal with. I'm someone that will send a plate of leftovers with a friend if they're over for a meal (do it all the time with mum and with one of my friends who is a single mum with a kidlet that won't eat much in terms of variety!)

drinks - depends on the situation - if they get put in a fridge, we tend to leave them unless asked to take them - if they're in our esky/drinks bag, we take them home.

DH has a friend that habitually turns up with six beers, drinks 10, then moves on to DH's top shelf stuff, and NEVER brings anything else - drives me nuts! on the odd occassion he brings more beer than he drinks (VERY rare), i won't remind him there is anything left in the fridge, but i check with everyone else - so it really does depend on the situation/relationship