I've done a lot of thinking and reading on the subject of gifts, gifting and gift economies this past 12 months.  There is a huge amount of acadmic work published on the subject.  Its one of those subjects that we all understand inherently but also find so fuzzy as to defy definition on closer examination. Lucy Kellaway in todays FT writes:    

There are two tests to mark out the generous gift.  The first, it must hurt a bit.  Second, you musn't shout about it.

Lucy is always worth reading. She has a knack for distilling down complex sociological concepts that otherwise fill entire shelves of dusty academic libraries into no nonsense tasty little bit-sized portions. Sample more from Lucy here: