Well, there are a too many cool features, but my top three picks are:
1) When you are seated at a window seat and if there is a black triangle symbol (No, Its not an Illuminati symbol!) just above your seat, then congratulations, you are on the ‘William Shatner’s seat. This is just a visual marker to identify the window/seat that gives the best possible view of the wing.
2) If you notice a small knob near the lever of your tray table, then congratulations, you are sitting in the Overwing Emergency Exit Row. (A320 and most other smaller planes). The knob helps to keep the tray table lever from moving into the open position as passengers squeeze between these seats to get to the Overwing Emergency Exit during evacuation. It prevents the tray table from opening and blocking the way to the exit. It also serves as a good visual identification and physical identification (when your cabin is dark and filled with thick smoke!) for the exit rows.
You would notice the other normal seats would not contain this knob.
3) Country of Origin & Aircraft Registration Number - This really obvious information painted on the side of the aircraft. Grab this number and run it through a search engine. You would find out many things about the aircraft - From current status (through Flight Tracker), to scheduled routes, earlier journeys, accident history, lease information, where the plane is stationed etc. Smaller jets, private planes & older planes (like the 747s/757s) reveal a lot of interesting information. It’s also an amazing feeling when you realize through the registration number that you are flying the exact same plane as you were on your last year’s Thanksgiving trip!