AGG supports:

• Reading and writing to JPEG files (it opens any JPEG file supported by jpeglib, i.e. essentialy every .JPG file you can come across); Reading/writing to .PNG and .BMP (a.k.a. Windows Bitmap) files;
• Creating simplistic .HTML galleries. No need of PHP / CGI / ASP / Java whatsoever;
• High-quality resizing using fully 32bit FP internal color processing pipeline;
• Organization of your images in project files, so gallery settings and rotation parameters aren't lost when you quit the program;
• Creating thumbnails with frame fadeout effect; combined with transparent .PNGs and your custom background can produce very beautiful results;
• Creating thumbnails for the galleries with mouse rollover effects;
• Creating multi-page galleries for faster loading;
• Supports SMP for fast operation on multi-CPU/multi-core systems;
• Full-featured support on Windows as well as Linux (and probably Mac OS X in the near future);
• Exif metadata in images. It is preserved in the output images and used for some cool things like:
• Figuring out image orientation (for digital cameras with orientation sensors);
• Figuring out image capture date, which could be used to put images in chronological order (especially if images are from several cameras);
• Generating an Exif stats page, where it places histograms for image settings like shutter speed, aperture, ISO speed and focal length
• Creating a .ZIP file with all images from the gallery;
• Per-image selection of output resolution.
• Image resizing and file renaming of whole directory hierarchies.

For details, consult the help files.