GIMP Plugin Registry is the largest known source of GIMP plug-ins where users can browse, download, comment and read useful tips related to GIMP. If you’re a GIMP user then you should not miss this site where you can find some useful plug-ins to power up your GIMP.
Here are some plug-ins I found very useful:
If you’re a Photoshop user, you will like this add-on. This is a series of scripts that similar to Photoshop Layer FX (effects). The effects you can apply are: Drop Shadow, Inner Shadow, Outer Glow, Inner Glow, Bevel and Emboss, Satin, Color Overlay, Gradient Overlay, Pattern Overlay, Stroke.
It is a set of various filters to apply, including: Arrays & Frames, Artistic, Black &White, Colors, Contours, Deformations, Degradations, Enhancement, Layers, Lights & Shadows, Patterns, Presets/Testing, Rendering, Sequences, Spectral Handling, Various.
This plug-in is very handy for web designers to save images optimized to minimal file size with acceptable quality. You may consider it as an alternative to Smush.it and Trimage. But with this one, users can adjust various settings, preview, compare and save images to lossless file formats.
This plug-in is for reducing image noise, useful for improving skin texture. It has a preview and good tooltips to help you deal with the settings.
Liquid Rescale is a plug-in to resize pictures non uniformly using seam carving algorithm. If you frequently resizing images to different sizes and aspect ratios, then you should have this tool.
This plug-in is a high pass filter, this filter is commonly used in digital image processing to perform image enhancements, sharpening and noise reduction.
For Ubuntu Users
If you are a Ubuntu user then you don’t have to manually install the plug-ins. It will be easier using Ubuntu Software Center, search using the keyword “gimp plugin”, click the plug-ins you want and let it install automatically for you. One thing I strongly recommend is the “repository of optional extensions for GIMP”, this package is a collection of many handy GIMP add-ons.