Wierd Coolant leak

[ynnek]

First off I have 1988 non turbo supra. I was driving around yesterday, actually heading to a salvage yard to get some parts for my room mates 1993 Honda Civic. Just as I was pulling into the salvage yard steam from coolant started rolling out from under my hood. Well I got towed home, added some water to the engine & cranked it to try & find the leak. Ther was nothing, nada. I let the car idle to operating temp & still nothing. I had my brother rev the motor while I looked for the leak & still nothing.
When I was in the salvage yard parking lot I could see a trickle running down near the oil filter. But when I ran the car at home there was nothing. I know this sounds a little vague, but can anyone help shed some light on this?