Natalie;
The entire area of Indonesia, including Sumatra, is a massive subduction zone, where the Australia plate is diving under the Sunda plate at a rate of about 2 inches per year. The 2004 Indian Ocean earthquake originated near here.
See http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=43506
The issue at hand is whether Toba could erupt again within our lifetimes… and the answer is "yes" it could. However, the same thing I said above about the Yellowstone Caldera also applies here… eruptions would be preceded by specific kinds of activity, and there would be warning signs. There is no evidence that a large and destructive eruption is imminent. The chances of it erupting in a so-called "supervolcano" eruption in our lifetimes is very, very remote. One of the smaller volcanoes around the caldera could erupt at any time, but then again we have several volcanoes across the world erupting… that's what they do.
I believe that the closest active volcano to me is Lassen… I'm actually not sure if Shasta is still considered 'active', but Lassen erupted (steam and gas) in 1917, I believe. The last time Shasta erupted would have been around 1785 or so.
Do I worry about them? No. Not at all. I'm more worried about earthquakes, and being a Californio I don't worry about them too much. I regard earthquakes as an opportunity to laugh at the tourists.
What I'm getting at is this: You are more likely to as a result of your eating and exercise habits than you are of anything having to do with natural disasters. Natural disasters make the news a lot, but then again they're kind of 'sexy' news items. At http://www.2012hoax.org/doomsday-objects#toc8 we make a point of publishing a table showing the causes of death, worldwide. Top two are heart attacks (6,880,000) and strokes (5,096,000).
Put those together and divide by 365, and you've got over 32,000 people dying every day from these two causes alone.
"Natural Disasters" doesn't even make the list.