I have had some success with MyPoints. You get 5 points just for a click-through and, as an example, need 5100 pts for 2500 UA miles.

But for me the most positive aspect of this program is that they offer lots of points for purchasing Entertainment Books. Earlier this year it was 1500 points per book, now its 1000. We would buy the books anyway, since they have $20 in Safeway coupons alone that just about pay for the book. Plus a couple of others that add up to about $50 in savings. Three books at 1500 pts each gets you almost to the level to redeem 2500 UA miles.