I've tried building tribal decks out of Rats and Snakes, which were abundant in Kamigawa. My Rats was a Standard deck, played like a casual deck, but is actually far more capable of shutting down decks than I had originally imagined. Creature removal, Distress and Ravenous Rats seem to be effective at shutting down decks. My Snake deck, was built just last night, and while it was playtested lightly in Apprentice, real life play showed a few crazy things that should never happen in casual Magic games. Thanks to the light playtesting it did go through in Apprentice, I found that my randomization was far worse than Apprentice could ever go. In one game, I drew all four of my Sosuke's Summons. In another, I drew 3 Loxodon Warhammers. Sosuke's Summons were made even better when I drew a lone snake: Seshiro the Anointed. I generated over 14 Snake tokens in that game. As for the game I drew 3 Loxodon Warhammers, I gained 32 life with a lone creature attacking in a single turn (with the help of Junkyo Bell), so I think I needn't elaborate further on how that game went ( I went from 8 life to 40 in one attack, needless to say, that was game).
Those were the only two Tribal decks I've tried. My younger brother has tried out building a Samurai deck (using tribal cards from the earlier blocks), but with little luck in the way of coming close to beating my Snake deck due to a mana problem. I've suggested to him the use of Gift of Estates to fix his mana - and I wonder if he'll take my suggestion. :D