I dunno too much about what overheating does to older honda auto trannies, but if too much heat can cause a loss of fluid viscosity in your tranny, it could slip?

Anyways, about the radiator... those things go out about every 6-7 years. That's just the problem with dealing with honda radiators, and it sounds like the car just went through it's second one...

What happened was that over the years, the plastic endcaps were exposed to stress from expanding and contracting at different rates, and eventually the radiator crack on this plastic piece, causing a massive loss of fluid...

So man, be a proper computer geek and bust out with that digicam! Show us exactly where the puddle is and where you think the crack is, and we can advise you from there. Also, the radiator is a simple install, and so you might be able to handle it yourself, or, if you don't want to risk anything, would be cheap to have done at a shop...