There are a few surveys or sweeps to signup for sometimes to get points. I can't remember them all, but they've been listed elsewhere on this board. I know Franklin Covey was one if it's still on the site. Also there should be emails that you can get points for just clicking on the links in them (usually 5-10 points per email). But the MyPoints folks must be on an extended vacation because we haven't seen many emails (only 3 or 4) since Christmas.
The bulk of the points I've earned have been from the great Tupperware deals lately (800 points for any purchase, etc.) and from ordering Lands' End merchandise through them which I was going to order anyway. Lands' End isn't "officially" a MyPoints Merchant (they're not in the QuickList), but if you go to a category like Apparel, there's usually a link on the right-hand side of the screen.
I'm sure others around here can give you a few more details.