I want one of these too, I'm not really much for mechnical edits. But this is really just for me to remember what I have done-.
Old Town, Stockholm
in 2005, I traced an old map of the old town and uploaded it, that data is long gone now.
in 2010, I tried adding IDs internal to the operator of the subway key:sl_realtime
Stockholm Archipelago and natural=land
in 2013, I retagged some and created ~1500 islands as natural=land in a feable attempt to make natural=coastline actually mean coast line for the mainland and not for islands. I got a bit of flack for that.. :-)