Even More Space Seat
For comparison, here's the Even More Space seat — JetBlue's version of premium economy — I sat in on my return flight. Still plenty of room to stretch out, and I was also able to board first with this seat (Mint class wasn't available on this plane). These seats vary in price depending on the flight, but I've read examples of them costing an extra $60 or $90 on top of the cost of a one-way ticket.
Other complimentary amenities all coach fliers can enjoy are WiFi (JetBlue's own Fly-Fi broadband Internet), charging outlets, a snack and drink station (with Doritos, chips, cookies, pretzels, etc.), and DirecTV (36 or 100-plus free channels depending on the aircraft). I will add that the plane makes a difference. The newer planes (with Mint Class) have a very cool inflight marketplace and more channel options.