Frequent flyer miles - we all rack them up on flights but rarely Cash them in for free vacations and upgrades. By one estimate, travelers collectively have accumulated nearly 20 trillion unused airline miles. Meanwhile the millions of miles in your frequent flier account are withering away, often expiring within a couple years. But did you know you can exchange those idle travel miles for cold hard cash? In recent years, a cottage industry has emerged to help consumers extract value from their stockpiled air miles. Specialty websites like Points.com and Mileage Plan offer cash or gift cards in exchange for unused airline reward miles. The payout isn’t huge - usually 1-2 cents per mile when converting to cash. But that spare change can ad d up, especially if you have piles of forgotten miles scattered across various airline loyalty programs. So how can you profit from those carryover frequent flier miles? Consolidating is key. Move all your airline miles into one rewards program to ...