a couple of ideas

[miraxis]

Have you thought of adding wigs that could be changed like the cloths?

 If you have a girl you like it would be cool if she could be a blond today, a redhead tomarrow, short and spiky then long and curly.

Also are cloths for the guys in the works? 

[pronzilla]

With some limitations, you can already do this by tweaking stuff behind-the-scenes.

Go read jak's tutorial about making bigger boobs: http://www.sexsim.com/forum/index.php/topic,40.0.html

In the xml files, look for <Hair>xxx</Hair> and <HairTex>yyy</HairTex>  You can mix-and-match the xxx and yyy with values from any of the ladies you have installed (though the textures/colours seem to be hairstyle-specific).  So, you can put robyn's hair on layla, or vice versa.  Presumably, if you have other ladies installed, you can mix up their hair, too. 

Hopefully someday we'll be able to come up with our own textures/colours.