Short time lurker - recent poster! Found this forum by way of cleanMPG.com (which I found by way of greenhybrid.com).
I've always been a tinkerer, and this forum is great in that everyone is trying new things and sharing their findings. In addition to the above mentioned sites, I also lurk at BITOG (oil related forum).
2005 Civic DX/Value Package Coupe with 4sp automatic
~18000 miles, lifetime MPG = 42.2MPG (personal best tank 48.5MPG)
OEM Dunlop SP20FE tires set at 45psi
Wayfinder v7500 (no real FE value, but it's a gadget)
Shopvac hose CAI (recently disconnected and back to factory setup)
coroplast undercarriage (have a 4x8 sheet of it in the garage)
moon disc hubcaps (ordered, just waiting for the UPS hookup)
IAT sensor override (maybe... have to read a bit more on it)
Civ Hybrid decklid lip (another maybe)
Welcome. You'll find that there are a lot of people here with great ideas. I hope to see your mileage stats as you are here longer.
Welcome to GS. I agree that the IAT mod may not work, but actual hot air could help. Instead of the CAI or stock intake, perhaps trying a hot air intake could improve FE. Depending on your location, an engine block heater could help in colder months to keep the engine ready for efficiency. Also, a hotter thermostat has helped some members. Remember to modify the driver too -- which has helped me a great deal. If you're daring, engine-off or neutral-only coasting adds up. I bet you could beat 50mpg easily. Good luck!