Wolfram|Alpha's goal is to make the world's knowledge computable. It's from the creator of the incredibly powerful Mathematica, and it provides straightforward answers to the questions it understands. Need to see a picture of myolglobin, determine which US president served the shortest time in office, or graph a 3-D wavy surface? Wolfram|Alpha can do it with ease.

It's a terrific curated resource, meaning experts deal with the content, so it doesn't suffer from the reliability problems that can afflict certain wikipedia articles and blogs. And it provides excellent citations, so you can find primary material or further information. It gives you one answer to each question, so there's no wading through 50 bazillion hits like Google sometimes provides.

The downside is that you are asking questions to an algorithm. As impressive as this algorithm is, it's not as good as a person at figuring out what you want. Ask what the chemical abbreviation DBA stands for, and you'll be told the definition of the word "abbreviation". Request information on dog allergies and you'll receive the lyrics to "How much is that doggie in the window". Everyday Wolfram|Alpha gets more knowledge and improves at answering questions. I'm not sure it will ever be able to compute everything, but it's definitely a handy tool to have in your research arsenal.