This addon will show the actual RAP bonus instead of the base bonus when mousing over the Hunter's Mark debuff.
It was based on a discontinued addon written by Sorata.
I have only tried it on an English client, but in theory it should work on all clients, as the addon finds out what the spells are called in the current locale.
It will also show when the Mark is at full strength as a combat text message. This particular bit is in English only currently.
Suggestions for improvements are welcome.