PlistChecker displays a report listing any problems it found.
BrothersoftEditor: After spending too many hours wondering why my document icons weren't showing up under Mac OS X, and finally figuring out that it was caused by a Typo in my 'plst' resource, I wrote this utility to help other Mac OS X programmers. Drag a packaged application, or a single-fork application containing a 'plst' resource, or an Info.plist file and drop it on PlistChecker. PlistChecker displays a report listing any problems it found.
What PListChecker does:
Verifies the UTF-8 encoding.
Reports any XML/plist parsing errors.
Reports any undocumented top-level keys.
Checks the types of the values for most documented keys, and keys within the CFBundleDocumentTypes, UTExportedTypeDeclarations, and UTImportedTypeDeclarations arrays.
Reports keys recommended by Apple documents that are missing from the plist.
These checks are based on my understanding of what a plist should look like, and should not be taken as gospel. PListChecker does not examine InfoPlist.strings files.