Sometimes candles drip wax beyond their designated area and said wax hardens on your table. Scraping it off can take some work and leave a residue, but you can avoid all of that trouble with an ice cube and a plastic card.
Instructables user kelleymarie explains what to do:
Place your ice cube directly on top of your hardened wax. If you are worried about water stains as the ice melts, put your ice cube in a ziplock before placing it on top of the wax. Wait two minutes. Remove the ice cube. Take your plastic card, and gently scrape your hardened wax off your wood surface. It should come off within seconds, if not replace your ice cube and wait for a longer period of time before trying to scrape up your wax.
This works best on hard surfaces. What should you do if you get wax in the carpet, on a towel, or elsewhere? She's got a variety of other tips, so check out her full post for more.
How To: Remove Wax Easily [Instructables]