Customs Duties Websites Links from various countries postal services.

Here's for Japan: http://www.customs.go.jp/english/c-answer_e/customsanswer_e.htm (it's the general FAQ page).

For some example of tax rates, here it is: http://www.customs.go.jp/english/c-answer_e/imtsukan/1204_e.htm

On top of that, there's also the 5% consumption tax and sometimes a handling fee (I only have two experiences of paying customs duty & tax: once with Fedex and the other was a USPS Priority Mail package; for both I had to pay around 200 yen of handling fee)

Thanks for that. It made my Fedex Bill easier to read. I just got charged tax for reimporting my bag into Japan, after it was repaired by Chanel USA! But the fee is probably not worth the hassle of challenging it.
 
Update: As of November 2011, for items being imported* from outside the European Union, the UK now charges VAT and/or other duties on items over GBP15 for commercial transactions and GBP40 for gifts between private individuals. It used to be GBP18, but that has dropped to 15.

See the full details on the Parcelforce website on their Customs Charging page.

*yes importing does include personal purchases over the internet. Look at this on the bright side, you are no longer an internet shopper, you are an international trader!:P
 
Update: As of November 2011, for items being imported* from outside the European Union, the UK now charges VAT and/or other duties on items over GBP15 for commercial transactions and GBP40 for gifts between private individuals. It used to be GBP18, but that has dropped to 15.

See the full details on the Parcelforce website on their Customs Charging page.

*yes importing does include personal purchases over the internet. Look at this on the bright side, you are no longer an internet shopper, you are an international trader!:P

Why am I not surprised? Any excuse to tax us further! I thought the gift limit was £36 though (i.e. double £18) so I suspect that will drop to £30 soon. They really ought to be increasing as those import limits were set in the 1970s.......oh well.