I'm in the process re-structuring my entire image library using nested groups in the keywords field and I have to say, this is a real milestone feature.
Many fields I used for images will be redundant by the time I'm finished, first one down is [people] which are now all in a keywords !People group, and working very well indeed. When I'm done, I'll see about getting some wiki pages done because for a long time I've asked that MC do for my images what it has done for my music, and as far as organising goes, this is one of the most useful and productive additions to MC in a long time, especially when coupled with the new 'list' related expression functions.
We can specify anything that we want to use as a separator, and that's not limited to a single character, so, if you place all your People tags into a !People group, you can then use the following expression to create a pane that gives a head count...
if(isequal(listcount([keywords],!People),2),1 person,
if(isequal(listcount([keywords],!People),3),2 people,
if(isequal(listcount([keywords],!People),4),3 people,
if(isequal(listcount([keywords],!People),5),4 people,
if(isequal(listcount([keywords],!People),6),5 people,
if(isequal(listcount([keywords],!People),7),6 people,
if(isequal(listcount([keywords],!People),8),7 people,
if(isequal(listcount([keywords],!People),9),8 people,
if(isequal(listcount([keywords],!People),10),9 people,
if(isequal(listcount([keywords],!People),11),10 people,No People))))))))))
I'll prattle on some more once I've finished reorganising, if you haven't looked at nested keywords yet, you should, I think you'll like them
-marko.