Geeqie can display files for which there are existing pixbuf loaders. In addition to the standard ones included with most distributions, the following loaders may also be available to you.
However, in some cases you are required to compile and install them yourself.
https://github.com/aruiz/webp-pixbuf-loader
https://gitorious.org/xcf-pixbuf-loader/mainline?p=xcf-pixbuf-loader:mainline.git;a=summary
https://cgit.sukimashita.com/gdk-pixbuf-psd.git/
If your distribution has the libpixbufloader-jasper.so loader, these file formats will also be displayed.