Using melted (carmelized) sugar is the most common method used by Scandinavian gingerbread house makers to glue together their gingerbread houses. However, sugar can brown too quickly.
Isomalt is a sugar substitute that can be used instead of real sugar to make sugar decorations (like the sugar showpieces on Food Network challenges). It does not brown as readily as real sugar, it doesn't "fog" up as badly and it is more resistant to humidity.
Here is a source for small quantities of Isomalt:
http://www.lepicerie.com/customer/product.php?productid=122029&cat=415&page=1
Obviously, it is more expensive than using real sugar. You can get it more cheaply, but you have to buy much larger quantities (you can do a Google search).
You might want to experiment first with real sugar to see if you even want to go this route. Working with hot sugar can be very dangerous, so be sure to clear everyone else out of the kitchen.
The basic recipe is to use twice as much sugar as water, and then to bring the solution to a boil and cook until it reaches 340F. Other ingredients may be added depending on the intended use.
Here is a link to some instructions on working with hot sugar (from a pastry chef's perspective):
http://members.aol.com/Noisykids/sugar.htm
And here is some information on candy making (from a home baker's perspective):
http://www.baking911.com/candy/101_intro.htm
http://www.baking911.com/candy/hard.htm
Good luck and BE CAREFUL!
Edith