Lava

Advantages Brilliant dominating point of decoration in any room
Disadvantages Takes a while to heat up

...One of my favourite purchases of all time, I think. I've always liked lava lamps but never seen one of such size (within affordability anyway). Being of such a size, they do require a high voltage light bulb which uses a large amount of electricity. Also, the lamps do take more than two hours to heat up and flow properly. But I think they're well worth the wait. They only come in two colour options: purple/red and blue/green. They could do with having more colours but I have the red and purple one in my room and it is a brilliant talking point to any visitors that come around. I paid £40 I think and that is a great bargain, specially compared to the Mathmos 'Astro' I think it's called.... Read review

Advantages Huge. Soothing. Good value.
Disadvantages Takes forever to heat up.

...A lava lamp is, in principle, very simple. It consists of a lamp, which heats up a glass bulb filled with a waxy solid and a liquid. These cannot mix together and must have very similar densities. As the solid heats up, its density is lowered, so it rises. This cools it down and it then falls to the bottom of the lamp, creating a strangely soothing effect. In practice, making one yourself would involve messing about with expensive and perhaps flammable chemicals, so I wouldn't bother trying. It is much easier just to buy one yourself. The Giant Grande Lava Lamp comes in two colours yellow and blue or yellow and violet. It is truly enormous at 27" and is guaranteed to be a focal point in your room. It is not called "giant" and "grande" for nothing! My lamp is a yellow and blue model. Although the product description says "yellow... Read review

Advantages Spectacular lava eruptions at night
Disadvantages Cloudy at times

...A volcano is like a candle, one year the lava drips on one side, the next year it drips on the other. We visited in March 2004, and stayed at the Hotel Arenal Los Lagos on the north face and could see the lava from our bed! You can find more info on this helpful site (we booked with them), a map of the lava flow & the locations of the hotels: http://www.arenal.net We explored the area because we plan on returning with our families. The hotels we saw with a direct view are: Los Lagos, Volcano Lodge, Arenal Paraiso, Montana de Fuego, and Tabacon. The los Lagos having the best trails, and best views. The Arenal Lodge is way out on the lake, with not a good view of the lava, being to far away. Often the area is cloudy, covering the crater, that's why it's important to stay in a hotel with direct view, just to be there when it clears up... Read review