What I think of is a sort of a mix between painting a UV map and using the sculpt tool.
It might be less computer-intensive to have some tools in the image editor that would mimick the sculpt brushes when editing a normal map.
This would be used like "sculpt" while keeping a small number of faces.

Everybody likes to save some disk space...

Particles baking is a useful feature, but the ".bphys" files are cumbersome.

For instance, I have created a project with (many) billboarded trees. The blendcache uses 510 MB.

- The same files compressed with bzip2 only use 97 MB.

Automatically compressing the .bphys files would save 81% of the disk space.

Since bzip2 is slow, these files could be compressed only when saving/quitting the project and uncompressed when opening it.

- With .gzip they use 137 MB. Gzip saves less space (73%), but it is much faster. So it could be used almost in real time.

I think that kind of improvement would be consistent with the automatic compression feature of .blend caches.

Sometimes, no matter how you unwrapped your mesh, which kind of image you try to bake to, this error keeps on popping up.

It seems to be a bug. But anyway it would be less frustrating if this error box included a selector for the user to force the selection of an image.

When I use "bake everything", the specular color is not baked, which is logical.

Then, when I render my picture with the baked UV, and make it shadeless, the object obviously looks duller. So I have to "fake" the specularity by increasing my map's contrast.

Currently only lamps can be made "spec only". The same option could be useful for materials.

Would it slow much the rendering ?

Currently in 2.46, to display particle as instances of a billboard, one needs to assign a texture to the source material.

Would it be possible to directly access to this from the particles panel, via an "IM:" selector in the "visualization" tab ?

By the way, this new system is a real improvement. Thanks to the developers !