I've used Sullivan's Quilt Basting Spray. It works well and seems to last for quite a while. I have a lap quilt here that I spray-basted at least a couple of months ago and it's still sticking. (Reminds me that I should get to that... :) ) What I don't like about it is that you need to spray where you have good ventilation. The fumes can be kind of bad. Also you have to put a sheet or something under the quilt you're going to spray because otherwise you'll have a sticky floor! I've found that you really need the sheet to be *at least* a foot larger on all sides. And finally you don't need to use too much of it. Sort of have to play with it. I try to cover the quilt with a very light layer of it and go back and re-do areas that don't seem to be sticking well.
Anyway hope this helps!