Big Fish Games again offers new customers any game download for Windows or Mac for $2.99 via coupon code "NEW299". That's tied with our January mention as one of the best deals we've seen from Big Fish Games in recent months, although we saw an offer for $1 games in November. (Many games are regularly $9.99.) Collector's editions are excluded.
A best bet is Midnight Mysteries: Haunted Houdini Deluxe for Windows (pictured) for $9.99 before coupon, or $2.99 after. That's $7 off and the lowest price we could find.