I'll get around to posting pics at some point, but I have a totally retarded process. I use Vallejo, but I've translated these into the (old) GW colours for simplicity.
1. Basecoat graveyard earth
2. Highlight (all but deepest recesses) 1:1 graveyard earth and bleached bone
3. Highlight bleached bone
4. Glaze graveyard earth
5. Highlight bleached bone
6. Highlight 1:1 bleached bone and skull white
7. Highlight skull white
8. Glaze bleached bone
9. Highlight skull white
This produces a really nice transition between shadow and light, and it would look really super impressive if I were actually a decent painter. As it is, the results are no more impressive than some of the basecoat+wash solutions on here.