I have created a group of HD texture packs that use the default textures for Minecraft. Why? Because, it is easier to create a texture pack from an already pre-sized guide! Also, you can test out various sizes to see if you can play with other texture packs of that size, before you install them just to find out that they don't work! These texture packs are useful for aspiring artists who happen to play Minecraft, as you can simply modify the textures however you want! It couldn't be easier! To use HD packs, you will need to install a mod or patch. You can use the HD patcher, however, I recommend Optifine, as it is much more useful than just enabling HD packs, it also allows more much more graphical tweaking, and when used correctly, can greatly increase your FPS.

Additional Notes

Optifine Thread:
www.minecraftforum.net/topic/249637-11-optifine-hd-a4-fps-boost-hd-textures-aa-af/

Texture Pack Download Links:

16x16 (NOT HD)
http://adf.ly/56Dri

32x32
http://adf.ly/56Dxf

64x64
http://adf.ly/56E2K

128x128
http://adf.ly/56E6h

256x256
http://adf.ly/56EAE