There's a long-running bug in Mapnik (the rendering engine for the tiles) that, when completed, will allow for SVG highway markers.
> Many users put their hometowns so that they're visible when you zoom out really far
Can you give more examples of this? More than likely it's due to problems with the import of TIGER data a couple years ago. It should have been fixed.
> There seems to be 80 airports in every county
Yea ... I'll give you that one :).
> It's incomplete in many places
... and in many more places it is more complete than Google, Yahoo, or Bing.
> It doesn't even give you directions
http://openstreetmap.org/ doesn't (the website is for the data and the community around it), but there are several examples of websites that do offer directions using OSM data: http://wiki.openstreetmap.org/wiki/Routing/OnlineRouters