I think there are a few things which constitute a trick well remembered, which may be stating the bleedin' obvious, but as magicollie would like to know they type of things people remember, I shall explain what in my experience is very memorable:
-Very visual magic: a bottle through table is very visual
-Very impossible magic (Impossible looking magic??

what the devil do you speak of?) By that I mean, magic which leaves the spectator NO room to think 'he did some slight of hand' 'They were a stooge' e.t.c
-Non Magical magic: Whilst card magic, and coin magic can be very entertaining and very well done, even I have a tough time remembering what how old tricks I used to do went as an effect. I think this is where it relates to the idea of borrowed or everyday items which I think seem to enhance the magic. People always tell me about things they saw on tv when they talk of magic, which seem to be things like people tearing other people in half, people walking on water, people tearing each other's faces off- in general not the type of stuff asociated with 'magic' (Cards, die, cups and balls- not they're weak... but not necesserily memorable. You can forgive me as a card worker).
On the subject of memorable magic- I try to leave each performance having given the audience something they can tell everyone about.. but I do not try to do it with every effect otherwise it can become saturated, I feel. People say when they saw Dunninger, that they don't really remember what he was doing but they remember he could read minds: which is a good thing in the sense that is they don't remember what it was you did, fully, they have no chance of working it out and every chance of hyperbolizing and 'airbrushing' (thanks Gordon Brown) the effects, but still, I want them to have something unique and memorable.
I think it is part of being a magician, and indeed one of the greatest things which makes it all worthwhile, is people talking to you about things you have done in the past and asking you to repeat them. There are many of these things, but one which even spooked me, was predicting, openly one day before, the Haiti disaster. More recently, I also predicted the plane thing going on today openly a week before that happened too. For the cynics, Let's just say I was *Ahem 'hurling the headlines'.
''To go wrong in one's own way is better than to go right in another's.'' Dostoevsky's Razumihin.