Also of interest, to Linux/UNIX/OS X users, may be the icoutils package (extract, convert icons etc).
Standalone command-line (Terminal) tool to convert Photoshop layered PSD files into Gimp's XCF (v1) format. Also may help recover damaged PSD files.
Very fast and reliable conversion (e.g. less than 2 seconds to convert a 40MB PSD to compressed XCF, on a 2004 model PC). Note: Currently converts image layers only.