Showed up one cold day to pick up a C-172, then fly to another airport to pick up some friends to fly to still another airport and found the a/c covered in frost. Spent a couple hours thoroughly scraping the frost off between rivet lines and had an interesting moment discovering climbout required considerably more pitch while having a low level look at the convenient creek bottom thoughtfully placed at the end of the runway. <img src="eek.gif" border="0">
After that I kept a couple extra jugs of automotive windshield deice fluid and a good squeegee/sponge combo in the car because no way am I taking off an a/c unless the wings SPARKLE.
In another vein, I checked with the Wardair chief pilot after witnessing an A310 take off with frost over the wing tanks because of cold-soaked fuel. Turned out that Airbus had done flight testing and had approvals for that operation.