First I also wanted to implement parallax mapping. But the problem with the visible seams around UV chunks entailed too much work on UV mapping. I want to be able to create meshes with color textures, normal maps, specular maps and ambient occlusion maps in Lightwave 3D and 3D-Coat (the former 3D-Brush) as fast as possible and without too many constraints.
For simple normal mapping I solved the seams problem more or less. If the normal of a fragment in tangent space is undisturbed (0.0, 0.0, 1.0), it gets only phong shading. For this I don't need tangent space calculations and can just use the averaged normals. As a result, if the tangent space normals in the UV border region are undisturbed, there is no seam visible.
One could have solved the seams problem with Nvidias Mesh Mender. But because I create this engine on my own, I didn't want to spend more time on this.
Now I'm working on a shadow map. After that I want want to look into post processing shaders and implement at least a bloom shader.