There's only moments of me being silly, here, but :
Aiel, Seanchan, and Randland - the 3 major distinct cultures at play
Rand, Moridin, LTT - long since assumed to be the case
Rand, Mat, Perrin - they'll finally feel like they have sort of a handle on women! Or they'll realize they all have some skill + some stupidity
Elayne, Min, Aviendha - how will Rand ever be able remember all their birthdays along with their individual anniversaries?
Human, Ogier, Nym (come back again) - three benevolent races combine to kick evil's butt!
Moridin, Rand, Fain - all three active good & evil forces
Borderlanders, Non-Borderlanders, Foreign Troops (Aiel, Seanchan, Seafolk) - you can also break it down that way
Egwene, Nynaeve, Elayne - Wonder Girls, activate!
Lan, Isam, Rand - they're all connected to each other by blood
The Three remaining Seals may also become one
The Three Outsider organizations - Aiel, Seanchan, Seafolk
Ishamael, Baalzamon, Elan Morin - substitute Moridin for Ishy, if you prefer, but it's still a name within a name within a name
Windfinder, Kin, Aes Sedai - the three channeling organizations (damane don't count)
Chocolate, Vanilla, Strawberry - I never ate the strawberry

This is part of why prophecies, like Nostradamus', can seem accurate. If I recall, Nostradamus had a prediction that seriously seems to anticipate the fall of the Twin Towers. When you couch your language in stuff like "and the two brothers shall fall," it has a wide applicability. God, I sound like such a nerd.