I have just read a question tagged cokriging, and this tag currently has only two questions under it.
I paid attention into this subject because I had previously helped curating the kriging tag (see: Are kriging questions getting enough attention?). When reviewing posts tagged 'kriging' many of them were about ordinary kriging, but there were also questions about regression kriging, universal kriging, simple kriging and also co-kriging (just use a simple search with kriging + keyword to see it).
Now, I wonder if it is worth having all types of kriging under one umbrella (the kriging tag) or having specific tags for each type of kriging. What do you think?