I'm currently doing an assignement for my Japanese class on gift giving customs in Japan.
If any Japanese people who would like to give their views on this topic, please either send me an email (eviltom03@hotmail.com) or post here.
I find it interesting that there are certain things that you're not allowed to give, such as a knife for a wedding, or green tea. It's also interesting the way omiyage are required, and the different levels of gifts.