After returning from a WoW break, I realised that the author of Power Auras Classic integrated these textures in the add-on since september 22nd 2009. Therefore, you do not have to download these textures seperately anymore. I'll just leave them here however for if someone wants to edit them or for possible future updates.
If you feel like using these textures as inspiration or for editing to your own liking, leave a comment here and I'll provide the original .PSD files.
Aura51 = Outer ring with glyphs
Aura52 = Outer ring without glyphs
Aura53 = Outer ring left glyph
Aura54 = Outer ring right glyph
Aura55 = Bottom half with glyphs
Aura56 = Bottom half without glyphs
Aura57 = Bottom half left glyph
Aura58 = Bottom half center glyph
Aura59 = Bottom half right glyph
NOTE: These textures have different numbers than the integrated ones in Power Auras Classic.
The bottom half has 3 glyphs inside of it. I use these for Serendipity as I play a Priest but they work great with other procs that go to 3, Lifebloom, Arcane Blast, etc.
On either side in the upper half circles, there is a glyph in either side, which can be used seperately or together, that's all up to the user!