Cheesy thread title? Oh well.
The Megami Tensei universe includes the following series:
Shin Megami Tensei
Digital Devil Saga
Devil Summoner
Persona seriesNow I must admit my own experience so far is only limited to some of the Persona games though I hope to eventually get a hold of and play the other games as they look quite interesting (Particularly, Digital Devil Saga)!
Anyway, here are some interesting essays/articles I found relating to P3 and P4 so if you haven't played those games all the way through you might want to be aware that these are full of spoilers:
http://www.destructoid.com/your-fate-is-in-the-cards-the-fool-s-journey-in-persona-3-116180.phtml
http://www.gamasutra.com/php-bin/news_index.php?story=22015
Kanji's such a great character.