Check this out (scroll down after [The Basics] 29):
http://xjaphx.wordpress.com/learning/tutorials/
Has some great tutorials like:
- Mean Removal effect
- Smooth effect
- Emboss effect
- Engraving effect
- Boost up color intensity
- Rounded Corner Image
- Watermarking on the fly
- Image Flipping / Mirroring
- Pixel Color Replacement
- Tint Color
- Flea / Noise Effect
- Black Filter (Increasing the Darkness)
- Snow Effect
- Shading Filter
- Saturation Filter
- Hue Filter
- Image Reflection Effect
- Draw Text on a Curve
