Press ~ to strikethrough (surround with <del> tags) selected text in MarkdownEditing

gistfile1.json

Add this to ~/Library/Application Support/Sublime Text 2/Packages/MarkdownEditing/Default (OSX).sublime-keymap
Will surround selected text with <del> tags when you type a tilde (~). Only works when text is selected.
Get Brett Terpstra's MarkdownEditing here: http://ttscoff.github.com/MarkdownEditing/


    { "keys": ["~"], "command": "insert_snippet", "args": {"contents": "<del>${0:$SELECTION}</del>"}, "context":
        [
            { "key": "setting.auto_match_enabled", "operator": "equal", "operand": true },
            { "key": "selection_empty", "operator": "equal", "operand": false, "match_all": true },
            { "key": "selector", "operator": "equal", "operand": "text.html.markdown", "match_all": true }
        ]
    },