The second entry in our series of engine and tool highlights is the amazing, general-purpose tile map editor, Tiled.  First released as a Java program back in 2004, Tiled has undergone some major revisions (including a full rewrite) and is now a stable and mature C++/Qt application boasting contributions from over 40 different developers.  Tiled is quite capable of handling any type of tile map you throw at it, including top-down, side view, or isometric.  And don't worry about having to load your map into another editor to add game-specific details -- Tiled is capable of placing game objects with pixel level precision and adding arbitrary metadata to maps, tiles, and objects.

Of particular note is Tiled's Automapping feature.  If you've used some other tile mapping programs (particularly ones built into various RPG creation kits), you may be familiar with the general idea and convenience of auto-tiles.  Tiled takes this several steps further by allowing you to define your own rules for automatic tile placement, which means you're not shoehorned into a particular tile configuration.  Here's a video tutorial of this feature as it is in the current release build (0.8):

If you're feeling like stepping into the nightly builds (which I'm told are robust in their own right), there are some new features included in automapping, as seen below:

Finally, Tiled is platform-agnostic, and there are a number of libraries out there capable of reading tiled maps (please note that not all of the libraries listed on that page are legal for entry into the Liberated Pixel Cup -- so if you're not sure, drop in on the LPC IRC channel and ask).