BuffSkin skins your buffs, simple!

Updated to 2.2:

You should now be able to properly select a gloss texture, as well as change it's alpha and size.
Added a few more textures.

Updated to 2.0:

Buffskin is now split into 2 separate addons: the teeny tiny bit which replaces the blizzard borders on buffs, and the configuration file which allows you to change the textures of these borders, and change the positioning of the border.

As the configuration file is now load on demand, if you don't open up the configuration, it'll never load! Making the addon even smaller. You can even delete the configuration addon entirely and buffskin will still happily skin your buffs like mad!

To add your own borders, simply create (or borrow) any .tga file you like, making sure that it is square, and dimensions that are a power of 2 (32, 64, etc)
Add the image into the BuffSkin/textures folder, and give it a name that hasnt already been used, for example "texture3.tga"

To change the configuration, type "/bs" or go to interface->Addons,
select the type of buff you wish to modify (buff/debuff/wepench), and drag the slider or select a different texture.

Quick howto: import your own textures.

Find the texture you want to use as the border, drop it into "Interface/AddOns/BuffSkin/textures"
rename it to "textureX.tga", where x is a number not already being used.

in game, type /buffskin, select the texture from the dropdown menu, resize it accordingly.

for gloss layers do exactly as above but use the gloss dropdown.

Note: This addon does not and will not ever resize or reposition the buffs.