You can now easily create a link to a position with a label. Right-click a spot on the map, select Add marker to create a temporary marker, drag the marker to the correct spot if it's not there yet, click the marker to open the info balloon, and click on Link to this position. At this point you can edit the label - the shown link will be updated to contain the label (with the correct URL encoding for special and international characters).
Multiple temporary markers are also supported, if you want to mark spots in the map. They only live in the memory of your browser, and are lost as soon as the map view is reloaded or the browser is closed.
The real-time map loading is now much faster by several seconds, or even tens of seconds in some cases. The speed-up was accomplished by not really initialising the date browsing menu before it's actually clicked and opened. The downside is that it now always shows the current and previous year, even if there is no data available for the previous year.
The AIS sites list is now generated automatically. There is a bug in there, causing some stations to not show up in the list. Still investigating that one.
When linking to a callsign, you can now add a parameter others=1 to show other stations, too.
When linking to coordinates, you can now specify a label, which will cause a marker to be shown at the coordinates, and a pop-up balloon showing the label to open.
The API terms have been updated, and a new FAQ item in the end describes the conditions for downloading data from aprs.fi.