Pillar
Pillar candles are usually fairly safe when burned for an hour or two at a time. If a pillar candle is left burning for too long, usually one of two things will happen: Larger pillar candles will melt too much wax and the wick will drown. Thinner pillar candles will get too hot, and the walls will grow soft, and may bulge or crack. This second situation can prove to be very messy, and potentially dangerous.
Taper
Tapers are often more wax-efficient than pillars. Because of the lack of wax above the flame, there are also few problems with molten wax drowning the wick. However, if the candle burns too quickly, then there is a good chance that the wax and flame can get out of control.
Tea Lights
Tea Lights are great because they are really small pillar candles. They come in their own little metal candle holder, so they're almost always drip-free and usually much more controlled than larger candles. If you have a tea light holder, just make sure that you have easy access to the candle to put it out if there is a problem.
Other
Novelty candles abound. Many are not meant to be actually burned (but most are designed to be OK if someone actually does decide to burn them). Be sure to read the warnings on these candles, especially gel candles.
Downloadable books (free):
William Godwin - The Lives Of The NecromancersAustin Osman Spare - The Focus Of Life
Aleister Crowley - Rights Of Man
Tuesday Lobsang Rampa - Chapters Of Life
