FileScanner is a Java application which can analyse the contents of several file types to tell you more about what they contain.
Are you curious about an EXE file, for instance? Just open it to view the DOS and PE headers. Each of these can be expanded to zoom in on an area of interest, and the program can display embedded image data, too.
Opening a ZIP file can be even more informative, as the program displays the archive header, data stream, directory and more.
There's support for common image file types, too, so for instance opening PNG, JPEG or BMP files will reveal the various chunks, markers and data blocks which make up the picture.
And the program does its best to help you, even if it doesn't understand the base file format you've selected. So there's no direct support for PDFs, for instance, but when we opened one it still scanned through the file, recognised some embedded JPEGs and told us more about them. (This kind of embedded image can also be exported as a stand-alone file.)
Although FileScanner doesn't directly understand Word's DOCX format, that's essentially just a ZIP file, so again it expanded the various file headers and data streams to provide useful information.
And there's always the hex view of the file, if all else fails. It may only be a beta, but already FileScanner is a useful tool for low-level file analysis.
A useful tool for low-level file analysis