Joel Spolsky has an article up call Why are the Microsoft Office file formats so complicated? (And some workarounds).
"Last week, Microsoft published the binary file formats for Office. These formats appear to be almost completely insane. The Excel 97-2003 file format is a 349 page PDF file.
If you started reading these documents with the hope of spending a weekend writing some spiffy code that imports Word documents into your blog system, or creates Excel-formatted spreadsheets with your personal finance data, the complexity and length of the spec probably cured you of that desire pretty darn quickly".
Also worth reading in his recent journal is TripIt is Awesome. TripIt is in fact awesome. Possibly teh.