How much does it cost (on average) to travel around the world for a year?

I don't think anyone answered your question. I just finished my first year of living nomadically while traveling. However, I didn't travel around the world. Still, I've done a lot of reading on this and can tell you that for a single person the average backpacker-style traveller spends about $1,200-$2,000 per month on a one year trip. Higher amounts for places like Europe, lower for India, yada yada yada. Budget 15-30k and you can do it, more is gravy. Don't forget to set some significant money aside for when you get back, perhaps 10k. Keep in mind that while you can travel very affordably for one year, the idea of "exploring the world thoroughly" in a year is not realistic. I spent almost a year in central america and hardly scratched the surface. It's a rich planet we have filled with culture, geography, and history. If you really want to explore it thoroughly don't set aside a year, work on how to make ongoing travel a sustainable lifestyle. I have done it and so can you!

A friend of mine wrote a blog post on it (http://www.casualhacker.net/blog/2009/08/traveling-around-the-world-logistics/). He paid $54,562 for his trip with his wife.  I don't know how average or standard this amount is, but it seems reasonable for that kind of trip to me.

Jenny McIver is a RTW traveler having been on 9 RTW trips so far. She racks up nearly 200,000 miles annually in the course of her business travel and puts all those miles to use on a "trip-of-a-lifetime" around the world. She spent $8000 for a trip across 16 countries. You can read about it at http://www.tripoto.com/trips/view/round-the-world-7-9531 You can read about all her RTW trips at http://www.tripoto.com/search?keywords=RTWand maybe connect with her for more details and advice on planning your own journey.

Given that very few people in the literal history of humanity have ever done this, it is hard to arrive at an average of any sort. The amount you have prescribed would be a pretty decent year of expenditures, especially if you will be going through South America or Southeast Asia or other places where the cost of living is significantly less than average. It is pretty tough to spend a few thousand dollars a month in some of those places unless you are staying solely in hotels instead of hostels, or are moving around a lot, taking planes instead of overland travel, eating fancy dinners, etc.

You should not underestimate the cost of the equipment. If your start from scratch you will need a good trekking backpack for a few hundred dollars. If you go to some regions with colder weather you will want to take a wind braker with an integrated fleece with you which will set you back another 100 - 500$. Together with trekking shoes, health kit, maps, travel guides, etc. the equipment can become a bigger part of your budget than originally planned.

It really depends on where you want to go. Asia is cheap, Australia - not so much. I've gone to Asia for 9 months and South America for 6 months before... As a rule of thumb, I usually budget $100 per day... this is way too high and I always come back with $$ in the bank. That $100 budget includes everything though, flights, food, hotels, splashing out once in a while. It's definitely not precise but is a good rule of thumb. I always rather go on a trip with too much $$ in the bank so that I don't miss out on anything though.

Traveling allows one to see new and old attractions in the city or country one is visiting. Traveling from one place to another results in expenses such as food, accommodation, entry fees to attractions and other emergency issues.In order to ensure that your travel is successful, you need to start a budget. A budget travel should include all details such as the type of activity to be undertaken, the cost and even the dates or duration of stayAttractions are a great way of learning the history of a particular city and as a traveler, you need to plan early. Use the internet to find attractions in the city you want to vacation in, know the prices charged and when they are open and closed. Planning early will ensure savings. Enjoy your travel !