Challenges:
1) Build a Cobble Stone generator.
2) Build a house.
3) Expand the island.
4) Make a melon farm.
5) Make a pumpkin farm.
6) Make a reed farm.
7) Make a wheat farm.
8) Make a giant red mushroom.
9) Build a bed.
10) Make 40 stone brick's.
11) Make atleast 20 torches.
12) Make an infinite water source.
13) Build a furnace.
14) Make a small lake.
15) Make a platform 24 blocks away from the island, for mobs to spawn.
16) Make 10 cactus green dye.
17) Make 10 mushroom stew.
18) Make 10 Jack 'o' lanterns.
19) Build 10 bookcases. (As of Minecraft 1.3, crafting bookcases is only possible if cows spawn on your island)
20) Make 10 bread.
21) Collect 10 Ender-pearls.
22) Cook 10 fish.
23) Craft 10 Black Wool.
24) Craft 10 Gray Wool.
25) Craft 10 Light Gray Wool.
26) Craft 10 Lime Green Wool.
27) Craft 10 Red Wool.
28) Craft 10 Yellow Wool.
29) Craft 10 Pink Wool.
30) Craft 10 Green Wool.
31) Craft 10 Orange Wool.
32) Craft 10 Snow Golems.
33) Craft 20 Paintings.