Bulbs

Outside the room are 3 switches.
Inside the room are 3 light bulbs.
Each bulb is connected to one of the three switches (each it's own).
You can play around the switches before going in the room as much as you want.
But once you open the door, you have to go in to examine the light bulbs and can't touch the switches anymore.

What's your strategy to find out which switch is for which bulb?

Spoiler : dont read if you dont know becase its the right thing :

Turn switch #1 on, turn switch #2 on for 15-20 minutes and play solitaire, then turn it off, and leave switch #3 alone. The #1 bulb will be on, the #2 will be off but hot, and the #3 will be off and cold.