There's several textures in Minecraft's default texture pack I felt like modifying. The blocks shown in the photo are currently the only ones I have changed.
-Changed windows, I hated those pixels in the middle blocking my view!
-Made a change to wooden door, which I will probably set back to normal
-Lapis ore is similar to all other ores in texture, as I did with emerald ore
-When released for 1.3, gravel will still have the usual texture that I believe is more realistic than the new one
- Added most new 1.3 blocks to the pack, though it's currently a 1.2.5 pack
-Regular pumpkins don't have faces, sucks for the snow golem!
-Jack-O-Lanterns have creeper faces
-Redstone is a lot simpler, good for those big circuits
-Minor change to powered and detector rails
-Ice
-Minor change to TNT
-Signs are simpler on the front, just to make reading easier
-Small change to furnaces
-Beds are blue, with a creeper face
-Cauldrons have a creeper face on the side
Planned:
-Better water and lava textures
-Aesthetic changes to chests
Bugs:
-When hitting chests, particles will have the Emerald block texture. This should be fixed in 1.3.

v0.4: Updated GUI for 1.3

I will accept suggestions for other changes.