The 1.2.5 minecraft seed Old Spice is great.  To begin with you spawn near an NPC village that is almost entirely submerged in water.   Its coordinates are X: 288 Z: 186.   There is a blacksmiths building in the village and it has 3 diamonds in the chest, Bonus!

Nearby the village at X: 196 Z: 121 is a huge pit, and it leads to a cave system that is great for exploring.  I only explored for a couple of minutes in the cave and I found some diamonds at X: 200 Y: 11 Z: 13.  I am sure there is plenty of other good finds in there for the intrepid spelunker.

A distance away at X: 13 Z: -382 is a second village in a desert biome.  There is another blacksmiths chest, but its contents are less exciting than the first.

In the same desert is a 3rd village at X: 119 Z: -675  …thats a lot of villages in pretty close proximity.

~thanks to Gaben1337