Put your hand up if you find your eyeliner transfers to your browbone about 20 minutes after applying it...
MAC have amazing eyeliners and I've found the Liquidlast to be the most non-budge I've ever tried. This does exactly what it says on the tin; it doesn't flake, it doesn't smudge, it's highly pigmented and you can get the most precise line with it.
The first time I tried this, I just whacked some on to see how it applied (so easily btw). A wee while later, I washed my face and eyes as normal, with Philosophy Purity and went off to bed without looking in the mirror. It wasn't until about 12 hours later, when I got up the following morning and looked in the mirror did I realise that it was still entirely intact across my lashline - it hadn't even started to crumble, peel or smudge!
They definitely require a good heavy duty oil based cleanser to remove them without having to scrub at your eye - you could try the Clinique 'Take the Day Off'.
So if you have oily lids and are looking for a super waterproof liner, want something that you can wear on the beach or simply just want one that lasts all day (and night!) long, get yourself to MAC and pick up one of these babies for about £13, although I bought mine for £11 I think at the airport.