If you can't find anything interesting left to explore here on Earth, your only resort is to look beyond the planet for a travel adventure. Ok, that's a little extreme when you consider all the things that Earth has to offer. Regardless, the new field of space tourism is starting to heat up and people are getting excited about the idea of getting out to space without having to join NASA.
To date, there have been 5 true space tourists, who have all been to the International Space Station (ISS) through the company Space Adventures.
Spending millions of dollars for the privilege, the following people have had the chance to explore space: Dennis Tito, Mark Shuttleworth, Gregory Olsen, Anousheh Ansari and Charles Simonyi. More tourist trips of this nature are scheduled in upcoming years.
Now, there are different levels of "space tourism". Visiting the ISS is the most sophisticated trip at the moment, but you can also view the Earth from sub-orbital elevations, which is considered by some to also be "space tourism". These trips are far cheaper, though still not really available to your everyday person.
If you are interested in either a trip to the ISS, orbiting the planet or even booking a seat on a future commercial trip to the moon, you should see what these various space tour companies have to offer.
As already mentioned, Space Adventures is known for facilitating tours to space for the wealthy. In fact, they are the only company who has actually put a paid tourist in space (so far). An orbital trip to the ISS start at $30-$40 million. Add on another $10 million and you can even experience the once-in-a-lifetime thrills of a real space-walk. For $100 million, you can reserve your place on an upcoming lunar mission.
For those with a few less million to spare, you could try a sub-orbital flight (that includes 5 minutes of weightlessness) for only $102,000. Other space related tours and training experiences are also available with Space Adventures.
Virgin was founded by Richard Branson, and will be offering sub-orbital space flights when their fleet of spaceships is completed. Flights start at $200,000 with the first commercial passenger flights anticipated for 2009. Their prototype ship has been built and they are currently working to develop the craft to be used in these flights. You can put a deposit down on a flight for only $20,000. According to their website, the privilege of being among the first 100 passengers is no longer available, as the list is filled.
Other companies such as SpaceX and Blue Origin are still testing and developing their space craft, and though they intend to offer commercial tourist flights, have yet to offer any concrete details, pricing or booking procedures.
Please note that most of these companies are in their development stage, and the best you can do is book a flight in the future, taking the risk that these companies are not going to be able to fulfil their ambitious plans.