Premise: The Settlers Online is not a quick game and there are many people (I am curious how many) that have remained with the game for years, not just building their island but helping to build the community. These individuals especially, I feel, should be acknowledged and celebrated in some way.
Proposition: There are two possibilities here, both the players birthday as well as the players anniversary date in game that can be celebrated.
On the eastern coast of the main island there are two small islands (sector 9 and sector 3) that see no activity, and so I propose that one be designated 'Birthday Island' and the other 'Anniversary Island'.
On the appointed day, on the appointed island, a cake building would appear (no need to number the birthday as some take that personally) that would provide a small bonus to all island production that day. As well, when the celebrating individual clicks on the cake they receive their present. Birthday presents would be the same each year, but anniversary presents should increment each year.
Also, visiting players can click on the cake to receive a birthday/anniversary buff token of some kind.