Materializations such as these often occur all over the world, in every culture. Often only very wise and talented people are able to do these kind of things. Still, I think it’s good to keep a healthy dose of scepticism towards these things 
Perhaps the most intriguing examples of materializations come from Tibetan tradition: they talk about tulpas, which are entities or thought forms which become reality with the aid of intense concentration and visualization. The tulpa masters often use dreams to strengthen their visualization/concentration powers. And when these powers reach a certain strength, the dream entities are able to cross the line between the dreaming and the waking.
To them, this phenomenon makes perfectly sense, since waking reality is just another illusionary level. However, creating a tulpa can be quite dangerous, if these tulpas are influenced by evil forces.
Perhaps the most famous tulpa story (except for a certain X-Files episode 
) comes from Alexandra David-Neel, who was the first Westerner ever to enter the forbidden city of Lhasa:
[i]When Alexandra David-Neel journeyed through Tibet, one of the many mystical techniques she studied was that of tulpa creation. A tulpa, according to traditional Tibetan doctrines, is an entity created by an act of imagination, rather like the fictional characters of a novelist, except that tulpas are not written down. David-Neel became so interested in the concept that she decided to try to create one.
The method involved was essentially intense concentration and visualization. David-Neel’s tulpa began its existence as a plump, benign little monk, similar to Friar Tuck. It was at first entirely subjective, but gradually, with practice, she was able to visualize the tulpa out there, like an imaginary ghost flitting about the real world.
In time the vision grew in clarity and substance until it was indistinguishable from physical reality-a sort of self-induced hallucination. But the day came when the hallucination slipped from her conscious control. She discovered that the monk would appear from time to time when she had not willed it. Furthermore her friendly little figure was slimming down and taking on a distinctly sinister aspect.
Eventually her companions, who where unaware of the mental disciplines she was practicing, began to ask about the “stranger” who had turned up in their camp-a clear indication that a creature which was no more that solidified imagination had definite objective reality.
At this point, David-Neel decided things had gone too far and applied different lamaist techniques to reabsorb the creature into her own mind. The tulpa proved very unwillling to face destruction in this way so that the process took several weeks and left its creator exhausted.[/i]
EDIT: @Morphius: I didn’t read your post until now, but I guess that you were also talking about tulpas?
Considering materializations: many famous hindu mystics had the apparent ability to do this. They showed it in front of thousands of people. For instance Sathya Saï Baba often materialized sacred ash, Vibhuti, and rings.