Some people build the USS Enterprise in Minecraft. Others recreate famous landmarks or buildings. The Hyrulecraft team instead decided to make a 1:1 scale representation of Ocarina of Time's Hyrule, right down to the garden where you first meet the princess. This is perhaps the most incredible Minecraft undertaking I have ever seen.
If you want to check it out, the alpha map can be downloaded here and the main server can be found at 188.8.131.52. Eventually, Hyrulecraft will include quests, dungeons, all the trimmings. I want to see how stuff like the Shadow Temple gets implemented. It's gonna be huge!