Marriott Rewards Plus Points launched a promotion in early to earn May 2,000 points/30 days, up to 12,000 max by Novemember 8, enter here. This requires linking social media accounts and completing certain actions, most easily twitter following specific Marriott properties at 250 points each. Doctor of Credit lays it out and helpfully provides links to the twitter accounts of the properties, see his post here.
Depending when you got in, this may already be the start of your 3rd 30 days. In my case I jumped in a month late, so did my 2nd batch today, prompted by calendar reminders.