if you make the soup stock/broth a day before and leave it in the fridge, you can skim off the congealed part that forms on top. and this goes for stews too.
A bit of trivia here, but I just read in latest issue of BBC's Good Food magazine that emptying oil, fat etc. down the sink in the UK is actually illegal! Not sure how they'd nick you for it, but it got me wondering if there are any other 'crimes' we might occasionally commit in the kitchen...
Hahahha! I guess they'll make those plumbers their informants. So whenever when you call a plumber to clear a clogged drain and if he finds out that it's because you've down oil in the sink, the plumber will report you to the authority! Eeeeeeeeeeee!
Another tip, soak in lettuce leaves, though it doesnt help much but at least take some oil from the food. The best way second to annebin.
I discard the oil and throw it in plastic bag.
My Chinese mother in law blows lightly on the surface of the soup to gather all the little spots of oil together at the opposite side to scoop off. This is after scooping as much as possible the normal way. A bit unhygenic, but it really works.
If you didn't make the soup in advance, and need to skim off oil when it's hot, pour all the liquid in a sturdy plastic bag (like zip loc). The oil will have floated to the top. Snip off a little corner and let the soup drain into a container. Stop when you get to the oil. I use this method for pan juice when I make gravy and it's really easy.