The following talk by G Dale is very interesting. It talks of his experience baling out of his glider after a mid air collision in the Club Class Nationals. As it happens, I was a couple of km away, heading into the same (crowded) thermal at the time - I saw a glider spinning down in the middle of the gaggle, and shortly afterwards, a parachute opening. He told the story in the bar that night. It's worth any glider pilot watching and reflecting on.
This video is very interesting in that it shows just how easy it is to lose site of the tug on an aerotow.
Flying a glider with an engine
Dave Nadler has written a good article about how to operate with an engine which you can find here.
There's also a very good talk on the design and manufacturing problems with glider engines below.
Landing with the wheels up
Here's a fascinating example of an aircraft landing wheels up (at Megeve altiport). All down the final approach you can here the undercarriage warning alarm. It's a good example of how hearing gets lost first when the pilot is loaded up.