What is it?
Where can I find it?
It is a free, patch modeler. It can be downloaded at http://www.geocities.com/hamapatch/program/index.html
Hamapatch has some pretty ugly bugs. I must say it´s easier to model in Blender. And hamapatch doesn´t have a bulti-in renderer or animation-capabilities.
So my advise is; stick to Blender. It´s even hard to export to blender from Hamapatch!
It is much quicker to make certain things in Hamapatch, it has its specialties. But you are correct that it is hard to export to blender from it. You have to save the patch file as a dxf mesh, and it often doesnt turn out good.
Yes, Hamapatch is good for modeling, but since it lacks animation-capabilities it is very limited. And the DXF-export capabilities sux! I tried to export a version of a dice made out of 6 circles in Hamapatch, but it looked like if the circles had only 8 points in Blender. (Though I where able to model the dice in Blender with Subsurfs). And the the dice lived happely ever after. 
Hamapatch has problems exporting to dxf because you creat splin models, but DXF is a mesh only format. Thus you lose tons of quality.