These scripts allow you to call Pandoc from within BBEdit or Textwrangler.
Unzip and copy the folder to ~/Library/Application Support/BBEdit/Scripts, replacing "BBEdit" with "TextWrangler" if you use the latter.
If you have BBEdit, copy pandoc-preview.sh to ~/Library/Application Support/BBEdit/Preview Filters (create this directory if it doesn't exist) to use Pandoc as a preview filter. Custom CSS files can be placed in ~/Library/Application Support/BBEdit/Preview CSS. Renaming the file to DefaultFilter_LanguageName.sh where "LanguageName" is the extension you use for markdown files will set Pandoc as the default preview filter (e.g. DefaultFilter_Text File.sh if you use .txt for pandoc files).
If the preview filter doesn't work, you may need to open the terminal, navigate to the preview filter, and use chmod +x pandoc-preview.sh to give the filter execute permissions.
To execute the scripts, open the Scripts Palette (Window: Palettes: Scripts) and select the desired output format. Keyboard shortcuts can be assigned from the Scripts Palette.
The scripts assume that your file is saved. Any error reports will be opened in a new text document.
It's straightforward to modify the scripts to include new output formats or customize the existing ones.
Including
open "${BB_DOC_PATH%%.*}".ext
where "ext" is the desired extension (e.g., pdf, docx) will tell your system to open the resulting output file using the default application for that type of document.