I bought a couple of sheets of this 3D printer build surface material from BuildTak when I was at Bay Area Maker Faire 2014. It works much better than the blue painters tape we were using on our 1st gen. Ultimaker at work, printing PLA plastic. The trick is in finding a material to which the printed plastic will adhere well enough for stable printing, but not so well that it is too difficult to remove the object when finished.
Note: As seen in the bottom-right photo, I wasn’t very careful laying down the sheet, and managed to trap a few air bubbles. Oops. Hopefully that won’t create any terrible problems with critical prints.
Get some here at BuildTak. This sheet was around $10 and should last for many, many prints. How many? I’ll let you know.