The folks at ProtoParadigm have produced a terrific list of tips on how to reduce or eliminate the deadly warping effect that plagues personal 3D printers.
There's nothing worse than discovering a time-consuming mess caused by a print that lifted off the bed. The warping itself isn't such a problem; it's that the warping can often be so severe that the print detaches from the print bed, tipping over and failing the job.
ProtoParadigm's advice includes a number of mechanical suggestions, such as ensuring your print bed is perfectly level and clean or adjusting first-layer speeds and heights. But they also explore the use of hair spray as a temporary adhesive.
Use of adhesives is not just a hacker's solution; 3D Systems uses it extensively in their Cube and CubeX personal 3D printers.
Here's ProtoParadigm's take on hair spray:
Yes, hair spray works for improving adhesion. A very modest application can do wonders. An over-application can create a bond strong enough that the object may be very difficult to remove, especially if you're printing directly on your build surface without tape.