Spam, please remove

You could ask the people from your local mountaineering club if they'ld like an introduction to OSM. Maybe they would be interested to map stuff like climbing routes as well.

I suggest you try to find a street that has been modified and use the item history to find out who did the change. Contact the user and tell him that his work was not really helpful. I blame most of these cases not on malice or lazyness, but people being both enthusiastic and clueless. Hopefully it's possible to give them a clue without demotivating them.

spam

Early this year the bavarian authorities released high resolution aerial photos for a trial period of three months, and by the end of that time quite a lot of landuse has been mapped. Doesn't look to bad IMHO; check for yourself at e.g. osm.org/go/0JWhIsy--
The area on the hill in the back would have been mapped as landuse=grass (one of the josm presets) probably, landuse=farm was used for actual fields.

I think we need a more general way of tagging danger areas; besides radioactivity that should also cover dangers created by unexploded ammunition or landmines.
On the topic of attack sites: That could be a value for the "historic" tag IMHO.

It might be better to just list the duplicate nodes and let a human being decide which one to delete or to merge (taking tags from one of them or both). I guess you have already thought of points that are part of a way, where they have to be replaced with the remaining node if a node gets deleted.

I "unstraightened" the line a bit in a place where it could be guessed from landsat and while I was at it also added a few river segments from the landsat image.

Eigentlich erkennt keepright solche Fehler auch ohne Einbahnstraße; entweder als "almost junction" oder als "intersection without junction".

Schau mal auf http://keepright.ipax.at/ auf der Europa-Fehlerkarte, da sollte diese Art Fehler eigentlich auftauchen.

Nicely done. I noticed notes labeled "list of tripoints" and "extreme points of montenegro" in your changeset that indicate that these where more than one point originally. Might be worth checking again.

You could use the new map history feature to find out who made a particular change; even if it was made by a script there should be a human being answering the mail. If to many "large" changes cover the area to find the user changing a small feature, use the element history provided in the data layer of the map.

I have not seen any vandalism on OSM so far, but there is probably some. However, most changes that make parts of the map worse than before are not malicious but simple mistakes. You can use the new area history function to find out who made a particular change and can just ask what the intention of it was. In case it was really vandalism, there are tools to "undo" a changeset.

Ich bin mir nicht sicher, ob die Nutzungsbedingungen eine Übernahme in OSM wirklich erlauben. Hat jemand mal konkret nachgefragt?

The line must be mistakenly shown by your editor, because there is no line in the data. Your changeset just contains the two campground nodes.

On a closer look: All the images served by b.tile.openstreetmap.org are missing. I can however load the image directly and it is displayed fine on its own, but even after doing that when the image should be in my cache, it is not displayed in the map.

Unfortunately, not fine for me. I have missing tiles in every zoom level and, using a 1024 x 768 browser window, basically everywhere on the map. On average about a quarter to a third of the tiles are missing; If i clear the cache, close and restart the browser and go back to a spot that I looked at before the same tiles as before are missing.

I'm not sure there is THE way to do things, but on your question about how to tag roads crossing waterways here is what I do: If there is an actual bridge I tag the bridge at layer 1 and leave the waterway at its default layer 0; if a stream is just passing under the road in a pipe or something similar, I tag the stream section passing under the road as layer "-1" and leave the road at default layer 0

Yes, I just noticed that farmland near by that IS being rendered by mapnik is actually tagged not as "farmland", but as "farm". Admittedly I didn't check the wiki yet; I just used what JOSM offered me to tag agricultural landuse.

While I have edited in that area in the last days (and the changes have been rendered already), that landuse=farmland has been there for more than a month.