MacHeist offers downloads of Scapple for Mac for free via the directions below. That's $15 off and the first time we've seen this mapping and productivity app for free. To get this deal:

1. Click here to start
2. click "Grab yours now!" towards the middle of the page
3. click the "Follow @MacHeist" button and sign into your Twitter account
4. click "Tweet" and tweet the message you're given
5. click "Get Scapple"