What text editor under OS X can close current window when you press ESC key

The default key bindings are stored in /System/Library/Frameworks/AppKit.framework/Resources/StandardKeyBinding.dict. You can use plutil to convert the file to an XML format, like so:

plutil -convert xml1 -o StandardKeyBinding.xml  /System/Library/Frameworks/AppKit.framework/Resources/StandardKeyBinding.dict

Or, if you have Xcode or Property List Editor, you can open it there.

In addition, you can add your own bindings system-wide to /Library/KeyBindings/DefaultKeyBinding.dict, or per-user to ~/Library/KeyBindings/DefaultKeyBinding.dict.

This page has a nice overview of bindings. I've grown particularly fond of Transpose (⌃-T), which swaps the two letters to the left and right of your cursor, fixing my most common kind of typo quickly.

In addition, there are various additional tricks using the ⌥ and ⌘ keys:

• ⌘-← and → move to the beginning or end of the line. Add ⇧ to select everything in between.
• ⌘-↑ and ↓ move to the beginning or end of the document. Add ⇧ to select everything in between.
• ⌥-← and → move to the beginning or end of the word, or between multiple words. Add ⇧ to select everything in between.
• ⌥-↑ and ↓ move to the beginning or end of the paragraph. Add ⇧ to select everything in between.

There's a large number of applications available that can do this.

My preferred text editor happens to be Byword. By default, it'll link to a specific dropbox folder (/Apps/Byword), but you can change this in the app's settings; just setting it to "/" will give access to every folder in your Dropbox.

iA Writer is another popular choice.

If you're looking for something more geared towards code than writing, Textastic is nice.

Additionally, Brett Terpstra has compiled a large list of iOS text editors and features here, though it doesn't specify which apps have full access or if they are limited to a specific App folder in Dropbox.